各校开运动会的田径项目比赛都要用到发令枪,枪响后,看到有白烟产生。该白烟的主要成分是[ ]
A.二氧化硫
B.二氧化碳
C.一氧化碳
D.五氧化二磷
答案:D
To enjoy the scenery,Tom would rather spend long hours on the train________travel by air.
[ ]
A.as
B.to
C.than
D.from