She often plans _____ something to help others.

Now China is fighting against illegal cooking oil（地沟油）, a kind of waste oil _____can cause a lot of illness.

My son prefers us to email each other once a weekspend half an hour on the phone every night.[ ]

It is no use trying to talk him into studying hard; he can only be by force.

Do you think it’s a good idea to make friends with your students— _____, I do. I think it’s a great idea.