Sally: It's because apple was very tasty.
CORRECT: It's because apple is very tasty.
EXPLANATION:
a. If we say "apple was very tasty" that means it was tasty before but now, it's not tasty anymore. We need to use 'is' instead of 'was'.

Sally: And I like color of the apple.
CORRECT: Also, I like the color of the apple.
EXPLANATION:
a. Avoid using conjunctions (BECAUSE, AND, BUT etc.) as first words in a formal sentence.
b. Whenever we talk about apples, there is only one color that comes in our mind - RED. So "apple's color" is a definite object, thus, it needs a definite article.

Sally: Also, apple has many vitamin then I would be a applie.
CORRECT: Also, apple has many vitamins, then I would be an apple.
EXPLANATION:
a. "Many" pertains to more than one thing. Thus, "vitamin" should be plural as well.
b. If the noun starts with a vowel (AEIOU), AN should be used instead of A.
c. Be careful with the spelling.

Sally: However apple is not good at eat at night.
CORRECT: However, apple is not good to eat at night.
EXPLANATION:
a. TO is the preposition used with a verb to make the infinitive.

Sally: but I thought apple is a good fruits.
CORRECT: However, I thought apple is a good fruit.
EXPLANATION:
a. Avoid using conjunctions (BECAUSE, AND, BUT etc.) as first words in a formal sentence.
b. We are talking about apples in general so we make it singular.

Hello, Sally! Thank you so much for submitting your homework. Please study the corrections that we have in here and if you do have questions feel free to ask about it. Have a goodnight! See you on Monday! Take care always! ^^

Love,
Teacher Belle.