1. The sun is rising in the east.
1-1. The sun is coming up in the east.
2. The sun is setting in the west.
2-2. the sun is going down in the west.
3. Don't look at the sun with your eyes for a long time. You will become blind.
4. Don't look at the sun with your naked eyes. It will harm/hurt/ache your eyes. You can become blind.
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Are they all grammatical? Would you correct unnatural sentences?
1 through 3 are fine.
If you use 'harm' in 4, that sentence will be correct, too.
1. The sun is rising in the east. (Grammatically correct)
1-1. The sun is coming up in the east. (Grammatically correct)
2. The sun is setting in the west. (Grammatically correct)
2-2. The sun is going down in the west. (Grammatically correct)
3. Don't look at the sun with your eyes for a long time. You will become blind. (Grammatically correct)
4. Don't look at the sun with your naked eyes. It will harm/hurt/ache your eyes. You can become blind. (Grammatically correct)
All the sentences you provided are grammatically correct. However, there are a few ways to enhance their clarity and readability:
1. The sun is rising in the east. (This sentence is clear and concise.)
1-1. The sun is coming up in the east. (This sentence is also clear and provides an alternative way to describe the sunrise.)
2. The sun is setting in the west. (This sentence is clear and concise.)
2-2. The sun is going down in the west. (This sentence is also clear and provides an alternative way to describe the sunset.)
3. Don't look at the sun with your eyes for a long time. You will become blind. (This sentence is clear but could be improved by adding a reason or explaining why looking at the sun for a long time can cause blindness.)
4. Don't look at the sun with your naked eyes. It can harm your eyes and potentially cause blindness. (This sentence is clear and provides more information about the potential consequences of looking at the sun with unprotected eyes.)
Overall, the sentences provided are grammatically correct, but some can be improved for clarity and readability.