Can people change their skin colour without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin colour. The gene comes in two versions, one of which is found in 99 per cent of Europeans. The other is found in 93 to 100 per cent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.

Scientists have changed the colour of a dark-striped zebra fish to uniform gold by inserting a version of the pigment (色素) gene into a young fish. As with humans, zebra fish skin colour is determined by pigment cells, which contain melanosomes (黑色素體). The number, size and darkness of melanosomes per pigment cell determines skin colour.

It appears that, like the golden zebra fish, light-skinned Europeans also have a mutation (突變)in the gene for melanosome production. This results in less pigmented skin. However, Keith Cheng, leader of the research team, points out that the mutation is different in human and zebra fish genes.

Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun, which can cause skin cancer. But when modern humans leave Africa to live in northern latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng. Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin colours, said Cheng.

The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin colour without damaging it like chemical treatment done on Michael Jackson.

1.According to the passage, scientists have found          .

A. people living in northern latitudes need more sunlight

B. the reason why people change their skin colour

C. the reason why people get skin cancer

D. the gene that determines skin colour

2.We can infer from the passage that         .

A. people like to change their skin colour

B. a mutation in the gene for melanosome production is different in human and zebra fish gene

C. people will be able to change their skin colour without chemical treatment in the future

D. skin cancer can be cured now

3.Which of the following is NOT mentioned according to the passage?

A. The version of the pigment gene of Asians and that of Africans are the same.

B. Scientists have succeeded in turning the colour of a dark-striped zebra fish into uniform gold.

C. Dark skin can protect bodies from utral-violet rays of the sun.

D. People like pop king Michael Jackson.

4.The passage is probably taken from __________.

A. a novel         B. a science report

C. a story book       D. a science fiction

 

Suppose you are Tom. While staying in Australia, you went on a wildlife safari(游獵), but you were very disappointed with the trip and you want to ask for half your money back.

Carefully read the brochure description below and the notes you have made and then write to the company covering the points in your notes and adding any other relevant information.

Write a letter of about 120 words.

（注：以下為宣傳手冊的內(nèi)容，其中斜體部分是你所做的記錄。）

Tropical Tours（熱帶旅游）

1-     Day Wildlife Safari $80

Relax and enjoy a unique experience!

Explore unspoilt rainforest, waterfalls and creeks

Observe an amazing variety of wildlife.

l         Travel by luxury air-conditioned coach     hardly modern!

l         Pick up from and return to your accommodation     one and a half hours late—missed dinner

l         Experienced guide with specialized knowledge of the area     but nobody could hear her

l         Swimming and guided rainforest walk            march! No time to enjoy it

l         Morning and afternoon refreshments(茶點) and a tropical lunch        sandwiches!

l         We supply binoculars(望遠(yuǎn)鏡)—a must for birdwatching. 

                                                      but not enough for everyone

As school starts again, there's so much more for an American parent to nag （嘮叨）about, like homework，bedtime and lost hours on the Internet.

But in the age of digital childhood，Jacky Longwell, 45 , of McLean, Virginia, often text – messages what she once told her children by mouth: Be nice to your brother; walk the dog; remember your reading.

This is the world of the modern family, in which even reminding children to do something has become electronic.

There are changes in how parents nag and in what they nag about and in how often of their nagging.

With technology," you nag more, and you are a little bit more precise （其體的）with your nagging,” said Reginald Black, 46, of Woodbridge. Virginia.

For many young people electronic nagging is part of the experience of growing up.

Charles Flowers, 17, a senior at St. John’s College High School in Washington, says his mother reminds him about everything from laundry, being on time to baseball practice and mowing the lawn by text.

When she uses capitals he knows she’s serious: GET HOME!

Some say technology has made nagging less annoying. Jacky Longwell thinks texts are less emotional than spoken messages and less likely to be resisted by teenagers.

“It’s not as painful for them to hear it by text. It becomes grouped with the friendly communication.” she said. “They can’t hear the nagging.”

She thinks a good way to do it is to mix friendliness with nagging. A parent can always start by saying hello.

Not all parents like the new electronic nagging. Joyce Bouchard, 51, a mother of four in Fairfax, Virginia , texts her 14 - year - old son but says that for many things-chores, homework-the old - fashioned way works better. Nagging by text has risks. She notes: “I always think, if you’re texting them something and they’re with their friends, they are getting a big laugh out of it.”

1. The main idea of the article is          .

     A. what American parents like to nag about

     B. why American parents like to nag their children

     C. how American parents began to nag their children by text messages

     D. that electronic nagging is becoming common in the US

2. The example of Reginald Black is used to show readers         .

     A. that her nagging is thoughtful

     B. that she likes nagging her children very much

     C. the kind of skills a parent needs to nag effectively

     D. how the amount and kind of nagging have changed with the arrival of the digital age

3.  The underlined sentence “Nagging by text has risks.” most probably means “           “

     A. Nagging messages may be resisted

     B. Electronic nagging costs too much

     C. Receiving texts is harmful to teenagers’ health

     D. Parents are likely to be addicted to nagging by text

4. We can infer from the article that          .

     A. it’s better for parents to nag in a friendly way

     B. if nagging is electronic, it is not annoying

     C. American parents generally don’t like to nag

     D. American parents like to use capital letters in messages

As school starts again, there's so much more for an American parent to nag （嘮叨）about, like homework，bedtime and lost hours on the Internet.

But in the age of digital childhood，Jacky Longwell, 45 , of McLean, Virginia, often text – messages what she once told her children by mouth: Be nice to your brother; walk the dog; remember your reading.

This is the world of the modern family, in which even reminding children to do something has become electronic.

There are changes in how parents nag and in what they nag about and in how often of their nagging.

With technology," you nag more, and you are a little bit more precise （其體的）with your nagging,” said Reginald Black, 46, of Woodbridge. Virginia.

For many young people electronic nagging is part of the experience of growing up.

Charles Flowers, 17, a senior at St. John’s College High School in Washington, says his mother reminds him about everything from laundry, being on time to baseball practice and mowing the lawn by text.

When she uses capitals he knows she’s serious: GET HOME!

Some say technology has made nagging less annoying. Jacky Longwell thinks texts are less emotional than spoken messages and less likely to be resisted by teenagers.

“It’s not as painful for them to hear it by text. It becomes grouped with the friendly communication.” she said. “They can’t hear the nagging.”

She thinks a good way to do it is to mix friendliness with nagging. A parent can always start by saying hello.

Not all parents like the new electronic nagging. Joyce Bouchard, 51, a mother of four in Fairfax, Virginia , texts her 14 - year - old son but says that for many things-chores, homework-the old - fashioned way works better. Nagging by text has risks. She notes: “I always think, if you’re texting them something and they’re with their friends, they are getting a big laugh out of it.”

68. The main idea of the article is          .

     A. what American parents like to nag about

     B. why American parents like to nag their children

     C. that electronic nagging is becoming common in the US

     D. how American parents began to nag their children by text messages

69. The example of Reginald Black is used to show readers         .

     A. that her nagging is thoughtful

     B. that she likes nagging her children very much

     C. the kind of skills a parent needs to nag effectively

     D. how the amount and kind of nagging have changed with the arrival of the digital age

70.  The underlined sentence “Nagging by text has risks.” most probably means“           ”

     A. Electronic nagging costs too much

     B. Nagging messages may he resisted

     C. Receiving texts is harmful to teenagers’ health

     D. Parents are likely to be addicted to nagging by text

71. We can infer from the article that          .

     A. it’s better for parents to nag in a friendly way

     B. if nagging is electronic, it is not annoying

     C. American parents generally don’t like to nag

     D. American parents like to use capital letters in messages