They had to_________ before they finishedthe course because they were not well disciplined

If you don’t know how to use the word, you should _________ in a dictionary.

I think there will be ______pollution and ______ carsin the future.

My cousin doesn’t know what to ________ at the university;he can’t make up his mind about his future.

Please do not feed the fish; they ________ die if they eat too much.