“after”后面应该跟现在完成时吧,表示过去发生并且已经完成的动作对现在造成影响或后果
After I have learned this word,I use it to make sentences.用used时，learn能用过去式吗那就得用learn的过去完成时，表示句中的动作发生在过去之前（过去的过去），即过去完成时动作发生在过去的过去：After I had learned this word,I use it to make sentences.