One third of our school _________ covered by trees, while the majority of our students ________ girls.

Make a tentative guess _____ Peking Man_____ have done and used thousands of years ago.

In Britain, people_______ four million tons of potatoes every year.[ ]

Jack is always occupied __________ his work, which makes him have no time to stay with his family

How can you expect him to make any improvement____ you never give him a chance to have a try?