__________ many times, he finally understood it.
Our .English teacher is our favorite. She’s kind and humorous, but____, she is strict with us.
---May I go to the cinema this evening? ---____. We should do the voluntary work in the nursing house.
—Don’t you know Li Ming will go abroad? —____, not until you ____me.
It is dark outside, so please____ your step while going down the stairs.
We can’t help you ____ you tell us what’s wrong.