I could hardly understand ______ in class, so I raised my hand to ask.
Beijing _________a lot in the last ten years. It is one of _________ in China.
We really don’t know _________ with our problems in learning English.
They were walking ________ a forest after they swam _______ the river .
_______should not be allowed to get ears pierced.
What would you do if you had _________ dollars ?