One must have a wide range of knowledge to ________ the changing market.

单项选择（每题1分）The stones each _____ as much as two tons.

Could you go to the bookshop with me I want to buy The Grass House by Cao Wenxuan.–Sorry, I . I’ve promised Mum to go home right after school.

ike some more cheese—Sorry, there’s _____ left

Our English teacher often uses different activities_ __ keep us_ __ in class.