“促进低碳经济”，警示温室效应对人类的危害．引起温室效应的主要气体是（ ）
A．CO2
B．N2
C．H2
D．O2
答案：A
将效果器接在调音台上便可以对磁带放出的音乐进行各种效果处理了。( )
–Many boy students think math is _____ English.
--I agree. I’m weak in English.
A．much difficult than
B．so difficult as
C．less difficult than
D．more difficult than
