我国目前用于砌体结构的砖主要可分为（）
A.烧结砖
B.非烧结砖
C.蒸压灰砂砖
D.蒸压粉煤灰砖
参考答案：A, B
—"I stayed at a hotel while in New York."
—"Oh, did you? You _____ with Barbara."
A．could have stayed
B．could stay
C．would stay
D．must have stayed
根据人眼的生理条件，视觉区域最佳夹角一般不小于（）
A.90°
B.45°
C.60°
D.30°
