【正文】
__to the Great Wall several times. A. go B. were going C. have gone D. have been 8. When we arrived , they _______dinner. A. had B. have C. were having D. are having 9. The students have cleaned the classroom,_______? A. so they B. don’t they C. have they D. haven’t they 10. I have been to the USA, ________________. A. so does Peter B. so Peter does C. so have Peter D. so has Peter haven’t discovered life on Mars ________. A just B yet C already D recently 12. Don’t talk so loudly .Your father _______. A. sleeps. B. is sleeping C. slept D. had slept 1 It ____ me half on hour to go to scho