Not until all the fish died in the lake __________ how serious the pollution was.
| A．did the villagers realize | B．the villagers realized |
| C．realized the villagers | D．do the villagers realize |
—— Will you stay for lunch?
—— Sorry, ＿＿＿＿＿. My brother is coming to see me.
| A．I mustn’t | B．I can’t | C．I needn’t | D．won’t |
—— Why do you make me do so?
—— I am sorry that you＿＿＿＿＿＿＿＿do such a thing.
| A．would | B．can | C．should | D．may |
—— Must I take a bus ?
—— No, you＿＿＿＿. You can walk from here.
| A．must not | B．don’t | C．don’t have to | D．had better not to |
—— I didn’t see her yesterday.
—— Oh, but you ＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿.
| A．must have | B．ought to | C．should have | D．cannot have |
They must have been here the day before yesterday,＿＿＿＿?
| A．mustn’t they | B．didn’t they | C．mustn’t have they | D．had they |