after可用作:
介词,后面跟名词、代词或动名词:
Let’s talk about it after dinner. 咱们吃完晚饭再谈这事。
She felt much better after taking the medicine. 吃完药后她感觉好多了。
连词,引导状语从句:
After we had finished the work we had a little rest. 干完活后我们休息了一会儿。
副词:
A moment after there was a knock at his door. 过了一会儿有人敲他的门。
afterwards(美式英语为afterward)为副词,表示“在这之后”“后来”等:
Afterward they had lunch in the garden. 在这之后他们在花园里吃了午饭。