I wonder ______ you’ll water this kind of tree. ——- Once a week.

It’s difficult for the village children to cross the river to get to school.— I think a bridge ________ over the river.

I don’t know the homework ______ today. [ ]

You look unhappy, what’s happening, my son? —I’m wondering how long it’ll be________ we come to China again.

My father arrived in Shanghai_____ the morning_____ May 21st. [ ]