그들은 두 명의 아이들을 입양했다=Adopted two children

=> Corrected : The sentence is corrected grammatically but there it's incomplete.

They adopted two children.​

넌 이 케이크를 얼릴 수 있어=You can freeze this cake

=> Corrected : The sentence is corrected grammatically but there is punctuation mark.

​You can freeze this cake​.

태양이 빛나고 있다=The sun is shining

​=> Corrected : The sentence is corrected grammatically but there is punctuation mark.

​The sun is shining.

Thank you, Eunchan~