根据短文内容，从方框中选择恰当的词，并将指代该词的字母填涂在答题卡的相应位置上。

A. information       B. different       C. see       D. send

We live on the planet（星球）Earth. Could we live on a 【小题1】 planet? To find out, scientists have been studying Mars for a long time. They 【小题2】 special machines to Mars. These machines are called rovers.

Scientists on Earth tell rovers what to do. Talking to rovers is something like playing a computer game. From Earth scientists can 【小题3】 what rovers are doing. Rovers usually move along the surface of Mars. They take pictures, study the planet and send the 【小题4】 back to Earth. They help us learn many things about Mars.