Do the sentences below sound natural? Also, are these true, you think?

For most Japanese people, the perfect present tense("have done") is very confusing because such tense doesn't exist in the Japanese language. Many learners, may include you, feel it hard to select the perfect present tense or the simple past tense("did") and the perfect present tense or the simple present tense("do"). To resolve this issue, you should know why the natives use the perfect present tense rather than the other.

There are two reasons why you use "have done" instead of "did": the current existence of the influence of that deed or the unsureness and insignificance of when the speaker performed it.

The present perfect tense expresses the connection between the past and the present. For example, "this theory was believed to be true," which implies the theory was proved false. In contrast, "this theory has been believed to be true" represents the theory remains true. "Have done" can show the current situation.

Besides this perspective, the present perfect tense shifts the focus from when it took place. For instance, if a man says to his friend about his trip to France last summer as an idle talk, he probably uses "went on." On the other hand, if he doesn't remember or doesn't focus on when he took it, he probably uses "have ever gone on." "Have done" can show something as just an experience in the vague past.

There is one reason why you use "have done" instead of "do": the speaker's focus on the action in this time.

The perfect present tense represents the current action. That doesn't regard it as a usual one. For example, "I eat a piece of bread as a breakfast" describes that the speaker eats bread almost every morning while "I have eaten a piece of bread as a breakfast this morning" doesn't imply that. The other breakfasts don't matter because the speaker is talking about this breakfast; he/she may want to say "it was tasty" or "I found I like rice rather" next. "Have done" separates the action from other counterparts.