影响混凝土碳化的因素很多,可归结为()两大类。
A.环境因素
B.设计使用年限
C.材料本身的性质
D.建筑物的功能用途
E.房屋的重要性类别
参考答案:A, C
-How are you?
-I'm 11 years old. [ ]
A. long
B. old
C. tall
There _____ many people in the park last Sunday.[ ]
A. had
B. was
C. were
D. are