与牙体缺损的原因有关的是( )
A.楔状缺损
B.重度磨耗
C.牙外伤
D.龋病
E.以上均正确
参考答案:E
解析: 牙周病只引起牙周组织的破坏,不会造成牙体缺损。
Could you tell me __________?[ ]
A. where do you live
B. who you are waiting for
C. who were you waiting for
D. where you live in
生产队预计30天修完一条水渠,先用18人修12天完成工程的1/2,如果要提前12天完工,还要增加多少人( )
A.20
B.18
C.36
D.12