一般婴幼儿开始出现有意注意的年龄（）。
A.2～3个月
B.3～4个月
C.12个月
D.6～7个月
E.8～9个月
参考答案：C
I argued ________ my good friends yesterday. What should I do? [ ]
A. of
B. with
C. at
D. to
6～14岁血红蛋白的低限为
A．100g/lB．110g/LC．120g/LD．90g/LE．125g/l
