after an hour ,an hour later用法有何区别呢
问题描述：
after an hour ,an hour later用法有何区别呢
例:Our maths teacher came to school at 8 and lef___________.
A.in an hour B.afer an hour C.an hour later D.before an hour
答
after an hour并无特指的时间点,而an hour later特指从现在起往后