英文文法!!!!

when a sentence contains already, yet..., it should be use 完成式
現在完成式: it means that you finished something from past to now
such as if you always swimming last 3 years, but you stop swimming now, then you must use 現在完成式.
For example: i have already finished all my homework.
Example 2: i have been learned English for five years.
過去完成式: it means you process it at the past
example: i had eaten an apple when i went out
未來完成式:it means you will finish it before certain time
Example: After 2 o'clock, i will have eaten an apple
if the sentence contains now , it should be use 進行式
現在進行式: that means you do it now
Example: i do the homework now
過去進行式: in past time , i am doing it
Example: last time, i was doing my homework
未來進行式: you also doing it in the future
Example: i will doing my homework later

進行式,完成式
their different is : is the event is already finish, and the time. When the event happened