Gloria: Vegetable is good at your healthy.
Correct: Vegetable is good for your health.

Gloria: My favorite color is pink and green.
Correct: My favorite colors are pink and green.
Explanation:   Singular means just one of the person, animal or thing
which the noun refers to and you will use "is". Plural means more than one and you will use "are".

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Hello, Gloria! Thank you for submitting your homework. Keep up the good work!

-Teacher Isabel