Remember the example sentence from part 1?

我们晚上吃了饭去看电影吧？

“了” means "finish", so you can also say 我们晚上吃完饭去看电影吧？

In these 2 sentences 吃了饭、吃完饭 have same meaning of "finish dinner".

If you ever learned 补语 (bǔ yǔ, complement) , the words follow and complete 谓语 (wèi yǔ ，predicate), some of the most common used like: 完、掉、好、到、成 etc.

“完、掉” and sometimes “好” all mean "finish". In this case, some people like to say “了” instead of complement words.

So which words we can use complement and we have to use? 忘、丢、关、喝、吃、咽、吞、泼、洒、扔、放、涂、抹、擦、碰、杀、卖、还 …… These sentences can also converted to “把” sentence, for example:

我想忘了他。── 我想把他忘了。

你扔了我的鞋子？ ── 你把我的鞋子扔了？

他卖了那本书。 ── 他把那本书卖了。

And these “把” sentences are more common used in our daily life, I well explain that in the future blog. More “了” explanation will be uploaded in my blog channel, please write to me if you have any questions.