根据短文内容，从A、B、C、D四个选项中选出一个能填入相应空格内的最佳答案，并把答题卡上对应题目的答案标号涂黑。

　　Senior high school life is a very new experience. Li Ruomeng, 16, a Senior 1 student at Shanghai No 8 High School, thinks that he has become more responsible (有责任感的) 41 he beg an to study in an all-boys class.

　　Li is studying in one of the first all-boys classes in Shanghai. The classes were started 42 September, 2012. Besides common subjects 43 math and English, the all-boys classes take some special courses. They’ve learned how to stay safe in earthquakes and fires. Li is looking forward to courses in the mountains. “That 44 be exciting and useful. I can’t wait to see if I can live by 45 in the mountains.” said Li.

　　From eight months of study, the students have got a lot from 46 and also made progress in their studies. But there are still some worries that boys in the class may be 47 to get on with girls.

　　Lu Qisheng, the school’s headmaster, doesn’t agree with that. “The boys told me they have more ways to get on with 48 ,” Lu told China Daily. “One boy goes to next-door classes to 49 girls stories, while another likes to show girls how to dance.”

　　The school is planning 50 four more all-boys classes this Sep tember. “What we try to do is to help boys do their best and achieve their greatest potential (潜能),” Lu said.

　　21. A. until B. after C. since D. when

　　22. A. at B. in C. on D. for

　　23. A. such as B. for example C. as D. because of

　　24. A. can’t B. must C. may D. shouldn’t

　　25. A. it self B. themselves C. myself D. yourself

　　26. A. their teachers B. common subjects C. special courses D. the mountains

　　27. A. clever B. friendly C. happy D. afraid

　　28. A . parents B. classmates C. teachers D. girls

　　29. A. tell B. say C. speak D. talk

　　30. A. to close B. to start C. to finish D. to give