Teenagers have all kinds of dreams. _____, some students would like to go to the moon some day. [ ]

______ unless I call you.

I think English is __________ unimportant subject.— I don’t think so. It is __________ useful tool when we talk with foreigners.

I read little now and I am always busy with my job. ________ my friend.

When will Mr Black come to Beijing?—_________ September 5.[ ]