Tom, _____ play games here. Father is relaxing. [ ]
A. doesn't
B. can't
C. don't
答案:C
下列物质的用途错误的是( )
A.硅是制造太阳能电池的常用材料
B.二氧化硅是制造光导纤维的材料
C.石英是制取水泥的原料
D.水玻璃可用作木材防火剂
* * 患病机会最多的象限是()
A.外上象限
B.外下象限
C.内下象限
D.内上象限
E.中央区