The second question:

The third question:

The fourth question:

This part of the extended information mainly examines the knowledge points of the present perfect tense:

It consists of "have/has+ past participle", which has two main meanings:

(1) said action happened in the past, but related to the present situation. Sometimes there is no adverbial of time, and sometimes it is used with some uncertain adverbial of past time, such as: many times, just now, however, once, never, always, before, up to now, up to now, etc.

(2) It means that actions that have continued from a certain time in the past to the present may continue. Used as a progressive verb, there are often adverbials of time in sentences, such as: two months, so far, etc.

Both the present perfect tense and the general past tense can indicate the action that happened in the past, but the present perfect tense indicates the influence of the past action on the present, indicating that the action has been completed or may continue; The past tense has nothing to do with the present situation, but only represents the past action, and this action has been terminated by the time of speaking.

Therefore, the present perfect tense cannot be used with adverbials indicating the past time, such as in 1949, yesterday, last week, etc. And when you ask these adverbial questions about time and place, you usually only use the simple past tense.