He had decided to give it up , but on____ second thoughts he decided to try___third time.
Half an hour has been made full ______ of _____ the problem.
Neither of them knows the difference ______ the two and we can’t tell one ______ the other, either.
— Smoking is bad for your health.— Yes, I know. But I simply can’t ____________ .
It was only when I reread his poems (诗) recently _____ I began to appreciate their beauty.
I ______ her to work hard at English, but she didn’t listen to me.