蓄水屋顶就是在刚性防水屋面上蓄一定厚度的水层,兼顾节能与()双重作用。 A.美观 发布时间:2019-03-10 10:23 │ 来源:www.tikuol.com 题型:单项选择题 问题: 蓄水屋顶就是在刚性防水屋面上蓄一定厚度的水层,兼顾节能与()双重作用。A.美观 B.经济 C.保护 D.环保
题型:单项选择题 函数f(x)=x2+ax+3,(1)若f(1-x)=f(1+x),求a的值;(2)在第(1)的前提下,当x∈[-2,2]时,求f(x)的最值,并说明当f(x)取最值时的x的值;(3)若f(x)≥a恒成立,求a的取值范围. 查看答案
题型:单项选择题 The cartoons made by the artists sell best, but several years ago no one could imagine how great a role he _____ in the field. [ ]A. was playing B. was to play C. had playedD. played 查看答案