A. Many of them wish to win international recognition.

B. They believe that more hands will make light work.

C. They want to follow closely the international trend.

D. Many of their projects have become complicated.

A. It requires mathematicians to work independently.

B. It is faced with many unprecedented challenges.

C. It lags behind other disciplines in collaboration.

D. It calls for more research funding to catch up.

A. Scientists tried to send a balloon to Venus.

B. Scientists discovered water on Venus.

C. Scientists found Venus had atmosphere.

D. Scientists observed Venus from a space vehicle.

A. It resembles Earth in many aspects.

B.It is the same as fiction has portrayed.

C.It is a paradise of romance for alien life.

D.It undergoes geological changes like Earth.