单项选择题

Why do scientists want to find out whether there is sufficient nitrogen on Mars（）

A．It influences the surface temperature of Mars.
B．It protects living beings from harmful rays.
C．It keeps a planet from overheating.
D．It is the main component of the air people breathe.

<上一题 目录 下一题>
热门 试题

单项选择题
What do we learn from the passage about sharks（）

A．They are not as dangerous as people think.
B．They can be as friendly to humans as dogs.
C．They attack human beings by nature.
D．They are really tame sea animals.
单项选择题
According to the speaker, what does the average negotiator usually do（）

A．Make sure there is no misunderstanding.
B．Try to persuade by giving various reasons.
C．Repeat the same reasons.
D．Listen carefully and patiently to the other party.
相关试题