点火提前角是指跳火时刻到该缸运行至压缩上止点时对应的曲轴转角
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They are_____their clothes.
A. making
B. putting
C. put away
D. putting on
Listen! She____in the classroom.
A. is singing
B. sing
C. to sing
D. is sing
_____are the birds doing? They are singing in a tree.
A. Who
B. What
C. How
D. Where
Look,They are swimming in the river.I want_____you.
A. to go with
B. go with
C. helping
D. help