龈上牙石最易沉积的牙面是（）
A.前牙的舌面
B.尖牙的舌面
C.前磨牙的颊面
D.磨牙的颊面
E.上颌第一磨牙的颊面和下颌前牙的舌面
参考答案：E
It's raining hard outside. You'd better _______ your raincoat if you go out. [ ]
A. put off
B. put away
C. put up
D. put on
墙体砌筑时，在预留构造柱位置旁的两侧墙体上竖向每隔（）留一皮砖高的无砂浆竖缝。
A.50mm
B.500mm
C.100mm
D.1000mm
