You can't go out and play before you finish doing your homework.
寫完作業之前，你不可以出去玩。
It will be weeks before they finish doing their homework.
要過好幾周他們才能完成家庭作業。
When you finish doing the crossword, the solution is on the back page.
在你完成填字游戲后，答案就在反面。
Can I just finish doing this? I won't be a minute.
讓我把這個干完好嗎？我很快就好。
Can I just finish doing this?
我能否就完成這件事？