Don't all speak at once ________,please.(1994)

问题描述:

Don't all speak at once ________,please.(1994)
A.Each at one time
B.One by one time
C.One for each tine
D.One at a time
说明原因

D,一次说一个
at one time 曾经 at a time,一次,其他的就不用解释啦