严重呕吐首先会引起（）丢失过多。
A.Na+
B.Ca2+
C.P
D.Cl-
E.Mg+
参考答案：D
She can't ride a bike. She ____________ school on foot.[ ]
A. must get to
B. has to get to
C. have to get to
D. has to go to
TRAS系统中的分析区是分析表中最基本的分析单位，分析区内必须是（）表元
A.字符型
B.浮点型
C.数值型
D.整型
