大体积混凝土温度控制标准有（）。
A.地基允许温差
B.上下层允许温差
C.内外允许温差
D.混凝土的搅拌温度
参考答案：A, B, C
已知小强今年14岁，奶奶62岁，那么（ ）年以后奶奶的年龄是小强的3倍。
We had never________this kind of holiday before and had no idea what to expect. [ ]
A. went
B. tried out
C. experienced
D. heard
