Don’t use water to put out the fire if oil catches fire. As is known, oil ____ float on water.

--Morn, must I clean my room now? --No, you          . You can do it tomorrow.

I can’t go to the cinema with you because I  _______ stay here until my mother comes back.

— Li Fan won the first prize in the national physics competition. — I ________ he was the winner.

Teachers should ___them to continue studying when some students want to give it up.