He asked me about the best way____ more English words

It is__________ his advice on how ___________English well_________ you a lot of trouble.[ ]

There are more than 740 million Chinese ______ to second-hand smoking in public places now.

The teacher explained a second time, thestudents should have difficulty in doing the experiment.

I’ll ___him off this time but next time he’ll bepunished.[ ]