单项选择题

The second paragraph is mainly concerned with ____________.

A．how the sun evolved
B．the structure of the sun
C．why scientists study the sun
D．the distance of the sun from the planets
<上一题 目录 下一题>
热门 试题

单项选择题
Besides its main use the noise-killing system can___________.
A．make a car lighter
B．make a car quieter
C．reduce the cost of a silencer
D．improve the performance of a silencer
单项选择题
The noise-killing system is not yet popular mainly because ____________.
A．it is still being tried out
B．drivers still have their doubts
C．it increases the cost of car production
D．carmakers are not sure if it is necessary
相关试题