上午AM和下午pm的怎么写

题目

上午AM和下午pm的怎么写
要大写的吗?中间要不要加点?a.m还是AM,Am,A.M?

答案

a.m.= A.M.
I go to school at 9 a.m.
p.m.= P.M.
We have supper at 6 p.m.
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