题目内容：

Scientists announced on Thursday, February 11, 2016, at a press conference in Washington, D. C that the more than half-century search for gravitational waves finally succeeded. They confirmed that they had detected gravitational waves caused by two black holes mixing together about 1. 3 billion years ago. It had been the first time the phenomenon was directly detected since it was predicted by Albert Einstein l00 years ago.

A China led space gravitational wave detection project is recruiting (招募) researchers from around the world, china news, com reported. The Tianqin project was started by Sun Yat-sen University in Zhuhhai. It centers on research of key technologies in space gravitational wave detection. To make the project more competitive，global talents in areas such as gravity theory，space gravity experiments and precision measurement are sought with an annual salary of up to 1 million yuan ($ 153.000). according to the report.

Gravitational waves are not easily detectable. When they reach the Earth, an extremely sensitive detector is needed, as other sources of noise can overwhelm the signal. Luo Jun. president of Sun Yat sen University said the detection of gravitational waves is a huge challenge and the project reflects the research competence of China.

The 15-billion yuan project aims to send wave-detection satellites into space in 15 to 20 years with construction of a research center and observatory to be started soon. Researchers will likely cooperate with other scientists from the European Space Agency’s LISA Project.

Gravitational waves are ripples (涟漪) in space time generated during the earliest moment of the universe, when the universe experienced a brief but disordered period of expansion. The detection of gravitational waves is believed to help scientists understand more mysteries of the universe.

1.What can we learn about gravitational waves?

A. They caused black holes to mix together.

B. They came out about half a century ago.

C. They wore proved true by Albert Einstein.

D. They have been discovered recently.

2.According to the passage, the Tianqin project is intended to      .

A. develop technologies to detect space gravitational waves

B. attract talented researchers from across the globe

C. conduct various space gravity experiments

D. seek precision measurement in space

3.The underlined word “overwhelm” in the third paragraph probably means “        .”

A. absorb    B. replace

C. remove    D. cover

4.The main purpose of the passage is to       .

A. explain the importance of the gravitational wave detection

B. present some new findings in space exploration

C. introduce a gravitational wave research project

D. encourage international cooperation in scientific research