空气中的（）能使涂料胶化变稠。
A.二氧化碳
B.氧气
C.氮气
D.水蒸气
参考答案：B
—I think this ________ is too short.
—What about the _______ one?
A．sweater; big
B．shoes; long
C．T-shirt; long
D．trousers; small
往返速比
