231A2G型化油器为单腔双喉管下吸式化油器。它由浮子室、气道及起动、主供油、（）、（）、（）五个工作装置组成。
参考答案：怠速；加浓；加速
－－What do you think has made Tom so excited?
－－_____ a prize in a lottery.
A．Winning
B．Won
C．He won
D．To win
How do you _____________ that? [ ]
A. does
B. do
C. doing
D. did
