Tom was about to close the window ______ his attention was caught by a bird.
| A．when | B．if | C．and | D．till |
The child was ____to go fishing alone because it was dangerous .
| A．allowed | B．required | C．forbidden | D．encouraged |
You ______ be hungry already — you had lunch only two hours ago!
| A．wouldn’t | B．can’t | C．mustn’t | D．needn’t |
The old tower must be saved, _______ the cost.
| A．however | B．whatever | C．whichever | D．wherever |
The book was written in 1946, ____the education system has witnessed great changes .
| A．when | B．during which | C．since then | D．since when |
---- It is demanded that the letter ___by the end of this week , dad !
----I’ll do it immediately .
| A．should mail | B．was mailed | C．mailed | D．be mailed |