Recently people have made great progress in using ____ power of nature to produce____ electricity.
| A．a; the | B．/; / | C．the; / | D．a; an |
The program is like a window on the world ____ you sit by it and fix your attention on what it shows.
| A．if | B．as | C．while | D．unless |
——Ms Lin looks rather a kind lady.
——But in fact she is cold and hard on us. You ____ believe it!
| A．shouldn’t | B．wouldn’t | C．mustn’t | D．needn’t |
Will you see to ____ that my birds are looked after well while I’m away?
| A．them | B．yourself | C．it | D．me |
The number 9.11 is a special number, ____, I think, that will be remembered by the Americans forever.
| A．what | B．it | C．which | D．one |
——You didn’t invite Mary to the ball?
——____ her, too?
| A．Must I invite | B．Should I have invited | C．Must I have invited | D．Should I invite |