In our class, when the bell rang and the teacher closed his book, it was a ______ for everyone to stand up.

A. signal B. chance

C. mark D. measure

The university estimates that living expenses for international students ________ around $8，450 a year, which ________ a burden for some of them.

A. are；is B. are；are

C. is；are D. is；is

Generally，students' inner motivation with high expectations from others ________ essential to their development.

A．is B．a(chǎn)re

C．was D．were

His comprehensive surveys have provided the most__________statements of how, and on whatbasis, data are collected.

A. explicit B. ambiguous

C. original D. arbitrary

In this article , you need to back up general statements with ________ examples.

A. specific B. permanent

C. abstract D. universal

Listening is thus an active, not a , behavior consisting of hearing, understanding and remembering.

A. considerate B. sensitive

C. reliable D. passive

Andy is content with the toy. It is he has ever got.

A. a better B. the better

C. a best D. the best

It was________of Michael to inform us of his delay in case we got worried.

A. careless B. considerate

C. patient D. generous

The police officers decided to conduct a thorough and _______ review of the case.

A. comprehensive B. complicated

C. conscious D. crucial

They gave money to the old people's home either ______ or through their companies.

A. legally B. sincerely

C. personally D. deliberately