如果ag某气体中含有的分子数为b,则cg该气体在标准状况下的体积是(NA为阿伏加德罗常数)[ ]
A.
B.
C.
D.
答案:A
某调研公司通过对A产品市场的调研得出:A产品的市场需求量虽然还在增长,但是销售量的增长速度已经开始减慢,很多同类产品已进入市场,竞争十分激烈。则我们一般可以认为A产品已经进入其生命周期中的( )
A.引入期
B.成长期
C.成熟期
D.衰退期
You'd better cut your hair short. Our school doesn't _____ long hair. [ ]
A. approve of students wearing
B. approve students to wear
C. approve students wearing
D. approve of students to wear