某气态烷烃与烯烃的混合气9g，其密度为相同状况下氢气密度的11.2倍，将混合气体通过足量的溴水，溴水增重4.2g，则原混合气体的组成为（　　）

A．甲烷与乙烯

B．乙烷与乙烯

C．甲烷与丙烯

D．甲烷与丁烯

Though the key was pressed, nothing ______ on the screen.

A．appeared

B．was appeared

C．appears

D．is appeared