凿硬岩时钎头的刃角一般为()。
A.90°
B.100°
C.110°
参考答案:C
I feel so excited! At this time tomorrow morning I to Shanghai.
A. will be flying
B. will fly
C. have been flying
D. have flown
下列化学方程式正确的是( )
A.Fe2O3+6HCl═2FeCl3+3H2O
B.Cu+2HCl═CuCl2+H2↑
C.2Fe+3H2SO4═Fe2(SO4)3+3H2↑
D.Al+HCl═AlCl+H2↑