Alvin: It's very long time ago since i meet you.
Correct: It's been a long time since I've seen you.

Alvin: Spring is warm.So my favorite season is spring.I alaways played with my friend in the spring
Correct: Spring is warm. It is my favorite season. I always played with my friend during spring.
Explanation: The pronoun "it" is used to represent a concept or  idea understood or previously stated.

Alvin: It so cool weather.I like this weather.Because It doesn't thirsty
Correct: The weather is cool. I like this weather because it doesn't make me feel thirsty.

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Hi, Alvin! Thank you for submitting your homework. Please take note of the corrections. See you tomorrow, Alvin!

-Teacher Isabel