Answer:
1. I knew what he had in mind for a long time. (Present perfect tense)
Ans: I have known what he had in mind for a long time.
2. He made the bookshelf himself in three months. (Past perfect continuous tense)
Ans: He had been making the bookshelf himself for three months.
3. I saw this painting a year ago. (Past perfect tense)
Ans: I had seen this painting a year ago.
4. I will teach in this school till June. (Future perfect continuous tense)
Ans: I will have been teaching in this school till June.
5. I will not tolerate this anymore. (Present Continuous Tense)
Ans: I am not tolerating this anymore.
Explanation:
In grammar, there are numerous tense forms that can change and completely alter the way sentences are used or written, or stated. It can also completely alter the whole meaning of the sentences. The given sentences changed to their required tense forms are as follows-
1.Ans: I have known what he had in mind for a long time.
Here, the action had already occurred in the past but the effect is felt in the present.
2.Ans: He had been making the bookshelf himself for three months.
The past perfect continuous form talks of a past event that happened and finished in the past.
3.Ans: I had seen this painting a year ago.
In this tense form, the events described had happened before some point in the past.
4. Ans: I will have been teaching in this school till June.
The future perfect continuous form describes or talks about an event that began sometime in the past, present, or even the future but would still continue in the future.
5.Ans: I am not tolerating this anymore.
The change in this sentence is from the future "will not" to present "am not", with the continuous form "verb+ing".
