A number of tourists _________ Yangzhou many timesbecause it is such a beautiful city.

If you buy ____ iphone 6s in our shopping mall， you will get ___ umbrella for free.

She is very hard-working, _____ he is very lazy.[ ]

_____ your letter, I would have written back two days ago. [ ]

Dale, what do you usually do school nights—I usually do my homework.