Most birds find it safe to sleep in the trees, but ____ they have eggs or young chicks, they don’t use a nest.
| A．why | B．how | C．unless | D．where |
The development of industry has been ______ gradual process throughout ______ human existence, from stone tools to modern technology.
| A．不填；the | B．the；a | C．a; 不填 | D．a; a |
We should get prepared for dealing with ________problems_________.
| A．any, arise | B．which, are arisen | C．whatever, arise | D．what, are arisen |
---You’ve read the Frog by Moyan , haven’t you?
---Yes, I_______ second time and I got a better understanding.
| A．have read a | B．had read the | C．will read the | D．read a |
We’ll never forget this terrible accident and the damage_______ has caused to the area.
| A．that | B．what | C．it | D．one |
--- You ought to have given them some advice.
--- , but who cared what I asked?
| A．I ought to | B．So I ought | C．So it was | D．So I did |