1.比較if only與only if
only if表示』只有』；if only則表示』如果……就好了』。 If only也可用於陳述語氣。
I wake up only if the alarm clock rings. 只有鬧鐘響了，我才會醒。
If only the alarm clock had rung. 當時鬧鐘響了，就好了。
If only he comes early. 但願他早點回來。
2.It is (high) time that
It is (high) time that 後面的從句謂語動詞要用過去式或用should加動詞原形，但should不可省略。
It is time that the children went to bed.
It is high time that the children should go to bed.
練習：
1.If only I _____ my watch!
A. hadn’t lost B. haven’t lost C. didn’t lost D. don’t lose
2.If only I ______ there.
A. have not been B. would not been C. will not be D. had not been
3.It is time we ______ up our results.
A. sum B. summed C. will sum D. would sum