操作动作规范化是指（）。
A.上车动作
B.驾驶姿势
C.下车动作
D.机件识别
参考答案：A, B, C
汽油车尾气中HC浓度比柴油车低。（）
What does the speaker mean
A．They have no time to practice.
B．This is the last practice.
C．They may not attend the show tomorrow.
D．They still need improving before they can perform the show.
