Hi, Jason! I've corrected your homework. Here are the corrections:
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The most unforgettable holiday that I had with my family was when we visited Ankor Wat in Cambodia during Chuseok Holiday 2 years ago. Cambodia might be one of the poorest countries in Asia. Ankor Wat was built in Cambodia's best days. I had seen their great and sophisticated architectures made of stone. So did my family. I have also felt their dark history, that is, Killing Field. I have seen many skeletons there. However, now Cambodians are very poor. Children always asked us for money and requested for us to buy something that they made. There were many popular attractions in Cambodia. Especially I hope that my sons felt that they were very wealthier than the children in Cambodia. In that point of view, Cambodia is very educational for my sons and my wife.

Explanation:
In your first sentence, you should put "was when we visited" to indicate the past action. For the next sentence, you mentioned the word "poorest" so it should be "countries" because you are comparing it to other countries. The next sentences also need to be in the past action. I think that you refer to people of Cambodia so you should write "Cambodians" and have the verb "are" to indicate the plural form of your subject. You can omit the word, "Especially" and start with your sentence. In comparing things with adjectives, if the word is already in comparative and superlative degree, no need to add the word "very".
These are some examples of adjectives in:

Comparative degree
Older
Younger
Colder

Superlative degree
Oldest
youngest
coldest

The words, "that" and "the" are necessary to make your sentence more appropriate. For the last sentence, I believe you mean to say "In that point of view" not "In terms of that point".
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Thank you very much for doing your homework, Jason! It's been nice to know about the most unforgettable holiday that you had with your family. I hope that you learned something in your homework. Again, Thank you and have a Great weekend!

~T.Cherry:)