对于主体结构砖砌体的应使用（）砌筑，若使用（）砌筑，砌体强度则会下降。
A.水泥砂浆
B.混合砂浆
C.石灰砂浆
参考答案：A, B
志愿军战士雷锋为抢救朝鲜落水儿童而牺牲。[ ]
— Mum, I've been studying English since 8 o'clock. _____ I go out and play with Tom for a while?
— No, I'm afraid not. Besides, it's raining outside now.[ ]
A. Can't
B. Wouldn't
C. May not
D. Won't
