You can't go out and play before you finish doing your homework.
写完作业之前，你不可以出去玩。
It will be weeks before they finish doing their homework.
要过好几周他们才能完成家庭作业。
When you finish doing the crossword, the solution is on the back page.
在你完成填字游戏后，答案就在反面。
Can I just finish doing this? I won't be a minute.
让我把这个干完好吗？我很快就好。
Can I just finish doing this?
我能否就完成这件事？