0.I am sorry to keep you waiting. I hope you_____long.(giải thích sao chọn với ạ) A. are not waiting B. don’t wait C. haven’t waited D. haven’t been waiting 1.It's about time you_____ the balcony. It's covered in leaves and dust.(giải thích sao chọn với ạ) A. cleaned B. had cleaned C. to be cleaned D. to have cleaned 2.Don't be silly! That_____possibly be David Beckham!(giải thích sao chọn với ạ) A. mustn't B. shouldn't C. won't D. can't 3.–“I locked myself out of my apartment. I didn't know what to do.”(giải thích sao chọn với ạ) –“You_____your roommate.” A. could have called B. may have called C. would have called D. must have called 4.–“Did the principal of the school answer you yet?” –“No, but____I hear from him by 5pm, I’ll let you know.”(giải thích sao chọn với ạ) A. might B. could C. would D. should 5._______help me make this decision. I’m just so unsure of which direction to take for my future. (giải thích sao chọn với ạ) A. I’d sooner you will B. I wish you will C. If only you could D. I’d rather you 6. _____ we have enough money, where would you like to travel this summer?(giải thích sao chọn với ạ) A. So that B. Provided that C. Despite the fact that D. Unless 7.Twenty people were arrested during the demonstration, of_____four were charged with obstruction. (giải thích sao chọn với ạ) A. who B. whom C. which D. them