动物必需的常量矿物元素有()。
A.7种
B.8种
C.9种
D.6种
参考答案:A
— Do I have to come back tomorrow?
— Yes, you _____. [ ]
A. can
B. may
C. must
D. should
曹操曾称赞谁“子真吾之樊哙也!”?