培养骨髓细胞时为避免返祖,定期用于处理细胞的是()。
A.PEG
B.TK
C.8-AG
D.HAT
E.ConA
参考答案:C
You look unhappy. What ________ just now? [ ]
A. did you happen
B. did happen to you
C. happened to you
D. you happened
社会关系的()和()使得社会关系的协调与平衡十分困难。