Washington D.C. is important because, capitol, white house, monument and the supreme court is in the Washington D.C.
Capitol makes laws. Judge works in a Supreme court. President lives and works in a White house.
I learned this.

Mary: Washington D.C. is important. Because, capitol,White house, monument and a supreme court in the Washington D.C.
Correct: Washington D.C. is important because, capitol, white house, monument and the supreme court is in Washington D.C.
Explanation:
a. Remember, you don't need to put period if the nextword that you will use is because.
b. Please study the usage of articles a and the. The definite article the is the same for all genders in singular and in plural. A singular noun beginning with a consonant.

Mary: Capitol makes laws. Judge works in a Supreme court. Prescident lives and works in a White house.
Correct: Capitol makes laws. Judge works in Supreme court. President lives and works in White house.
Explanation: Be careful of you spelling always. I omit a because it's not necessary in your sentence.

Mary: I reivewed these.
Correct: I studied this.
Explanation: Instead of using reviewed you have to use studied because this is more appropriate in your sentence.

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Hello Mary^^

Good Job for this homework. I am happy because you learned something in class. Keep it up!

Love,

Teacher Mary ^^