—______ your backpack?
—Yes, it is. [ ]
A. It is
B. Is that
C. That is
D. This is
答案:B
已知f(x)是R上的奇函数,则f(0)的值为( )
A.1
B.-1
C.0
D.不确定
0.9%氯化钠80ml,10%葡萄糖80ml,张力为()
A.等张
B.1/2张
C.1/3张
D.1/5张
E.2/3张