1. There is one more point that I want to talk about.

2. There is one more point we have to think of.
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Are the sentences grammatical? What is the meaning of 'point' here?

3. The farmere wanted to get rid of the hawks. So with the help of officials, they could kill all the hawks. However, they found that field mice were growing in number. Field mice ate up their grains. Hawks not only eat chickens but also field mice. Then the farmers came to know that it is always necessary to keep the balance of nature.
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Q1: In the passage, what is the meaning of 'then' in the third line from the bottom? 'At that time' or 'after that'?

Q2: Came to know, got to know, learned to know......Are they all interchangable?

1 and 2 -- Yes, they are grammatically correct. The word "point" means "idea" in this sentence.

Q1 ... yes, you're right

Q2 ... yes, they mean approximately the same thing, but the third one is not used much (or at all!).

1. Yes, both sentences are grammatically correct.

In both sentences, the word 'point' refers to an additional topic or aspect that the speaker or writer wants to discuss or consider. It is often used to indicate that there is something else to be mentioned or thought about in addition to what has already been discussed.

2. Now let's answer your additional questions about the passage:

Q1: In the passage, the word 'then' in the third line from the bottom means 'after that'. It suggests that as a result of the farmers' realization regarding the importance of maintaining the balance of nature, they came to understand the significance of keeping the natural predator-prey relationship intact.

Q2: 'Came to know', 'got to know', and 'learned to know' can all be used interchangeably to convey the same meaning - gaining knowledge or becoming aware of something. They all express the idea of acquiring information or understanding about a certain topic or situation.