英语语法

Question

After having read numerous diet books, Charles decided that the simplest plan would be the best: eat fewer calories and exercise more. Not having traveled abroad before, John was both apprehensive and excited. 这两个句子after having 和not having是什么时态，这个句子为什么逗号后面是一般过去时？ 这一类的语法是什么，有什么注意的，谢谢
前句是现在完成时，后面是过去时，这个句子中的时态搭配合理吗？

Answer 1

after having done是以现在分词的完成形式作时间状语,表示这动作在谓语所表示的动作之前发生,即decide发生在read之后
这段话时态都是过去时，所以用decided

下面是一些基本时态
一般现在时:用动词原形
一般过去时:用动词的过去式
一般将来时:will/shall+do
is/am/are going to do
过去将来时:could/would do
现在完成时:have/has done
过去完成时:had done
将来完成时:shall have done
过去将来完成时:would/could have done
现在进行时:is/am/are doing
过去进行时:was/were doing
将来进行时:will/shall be doing
过去将来进行时:would/could be doing
现在完成进行时:have/has been doing
过去完成进行时:had been doing
将来完成进行时:shall have been doing
过去将来完成进行时:would have been doing

Answer 2

after是介词后用动名词having，not having是动名词作主语。因为两句中后面的动作都 在前面动作之后，前面用完成时，所以后面应用过去时