Today is . The students want to buy some things for their teachers.

You should let your children play ______ you can see them.

The water will be polluted unless some measures _____

Sir, could you please wait for another 20 minutes and we’ll serve you very soon– Another 20 minutes? It was only 6 o’clock ________ I got here, but it’s 7∶10 now

We haven’t seen the film _______.