Shanghai will host the World Expo _____May.[ ]
A. in
B. on
C. to
D. at
答案:A
煤与瓦斯突出多数发生在构造带、煤层遭受严重破坏的地带、煤层产状发生显著变化的地带、煤层硬度系数小于( )的软煤层中。
A.0.5
B.1
C.1.5
D.2.0
D
In 1847 most countries of the world were ______.
A.not yet using stamps
B.collecting valuable stamps
C.buying stamps for Mauritius
D.printing their own stamps