细胞内液主要阳离子为（）
A.钾离子
B.锌离子
C.钙离子
D.钠离子
E.氯离子
参考答案：A
Tom told the boss of his company that he ______ born in 1956.[ ]
A. was
B. had been
C. is
D. has been
国标中规定基本视图共有（）个。
A.3
B.4
C.6
