2.1 课时作业
Ⅰ.用所给词的适当形式填空
1．With the telescope, they can observe distant stars that are ________ (visible) to the naked eyes.
2．At the shot, the birds immediately flew away in all ________ (direct)．
3．He lay ________ (wake) for the whole night, worrying about his lost child.
4．________ (rough) speaking, it was about 30 kilometres' ride.
