题目

  根据对话内容,从对话后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。 Sandy is at home. She is now calling Lisa, her classmate. Sandy: Hi, Lisa. Have you finished helping your parents? Lisa: I finished cleaning the living room a little while ago, but I haven’t cleaned my bedroom yet. 61 Sandy: I know what you mean. 62  Do you think you’ll be finished soon? Lisa: I should be done in about an hour. Sandy: 63   Lisa: I did the English homework last night. 64  I don’t understand it. Sandy: Me neither. 65 We can help each othe已知向量a=(cosθ,sinθ),b=(,-1),则|2a-b|的最大值为(　　)(A)4(B)4(C)16(D)8