石油中的烃类不包括()
A、烷烃
B、环烷烃
C、芳香烃
D、烯烃
参考答案:D
Many people don't like winter because it's _________ cold. [ ]
A. too much
B. much too
C. too many
D. much more
产品销售增长减慢,利润增长值接近于0时,此产品已进入产品生命周期的()。
A.导入期
B.成长期
C.成熟期
D.衰退期