That is Beckham. He was born _____1975. [ ]
A. at
B. on
C. in
D. to
答案：C
进行萃取操作时，应使溶质的分配系数大于1。
骨骼肌细胞动作电位降支形成的原因是
A．Na+内流B．Cl-内流C．Ca2+内流D．K+内流E．K+外流
