—Look! What a nice classroom!      — Yes, it ________ every day.

A. is cleaning                   B. has cleaned      C. is cleaned

--Must I clean the classroom now, Miss Wang?

--No, you needn’t . It                by Bill.

A. is cleaning     B. should be clean  

C. was cleaned     D. has been cleaned

It’s hard to keep the house       with two kids in it.

More and more Americans are going to work by bike. Do you know why more people are  41   bikes to work? We can answer the question in  42  ways. First, bikes don’t need gasoline (汽油), so it takes  43  money to use them. Second, a bike doesn’t  44 much space (空間), so it is  45 to find a                   place for it. And riding a bike is good for one’s  46 . People often drive their  47 to offices or to shops, but now people think riding bikes is a good way of doing sports.

That’s  48  more Americans are now riding to work  49  bike, and they are  50  their own cars at home.

根據(jù)短文的內容，從A,B,C,D四個選項中選擇最合適的答案填在括號里
The Spring Festival is the Chinese New Year’s Day. It usually   41  in February. Everyone in   42  likes the Spring Festival very much. When Spring Festival comes, Li Lei usually helps his parents   43  their house and do some   44   and other housework.   45  that day everyone in China eats   46   ， New year’s cake and some other   47  food. Li Lei likes New Year’s cake,  48 Wang Lin says jiaozi is better than New Year’s cake. He thinks jiaozi can  49  us good luck. Chinese people eat the New Year’s cake and jiaozi in their houses.   50   happy they are!