单项选择题
A．The deadline is drawing near. B．She can’t meet the deadline. C．She turned in the proposals today. D．They are two days ahead of time.
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.
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.