出现沙尘天气时，大量微尘在空中悬浮，这些微粒对光的散射，天空呈现橙黄色．

（1）橙黄色光在大气层中的光速近似______km/s．

（2）一般沙尘天气，风力发电机可以正常工作，将风能转化为______能．

（3）沙尘以12m/s的速度运动时具有的动能为1.008×10⁹J，风力发电机输出的电能为2.016×10⁸J，这台风力发电机的发电的效率是______．

Ten years ago the population of our village was ________that of theirs.

A．as twice large as

B．twice as large as

C．twice as much as

D．as twice much as