Don’t all speak at once! , please.
A. Each at one time
B. One by one time
C. One for each time
D. One at a time
网友回答
A. Each at one time
B. One by one time
C. One for each time
(答案→)D. One at a time
解析：解题干句（信息句）的意思是关键。Don't all speak at once !的意思是：不要都同时讲。由此，根据提示句的含义及备选答案，我们可以判断后面的意思应该是：请每次一个。上面四个备选答案中One at a time 的意思是每次一个。at a time是“一次”的意思。所以选D。