炎帝和黄帝部落主要活动于 [ ]
A.黄河流域
B.长江流域
C.黄淮平原
D.黄土高原
答案:A
一根完整的股骨是一个( )
A.细胞
B.组织
C.器官
D.系统
—Why didn't you come to my party? I was so disappointed at your absence.
—I'm very sorry. I ________ but I had a visitor at the last minute.[ ]
A. would like have
B. would like to
C. had planned to
D. were going to