YOU SAID:

I'm so tired that i dreamt of a cat and a dog and a mouse taking a test

INTO JAPANESE

私は猫と犬とマウスがテストを受けることを夢見ていたのでとても疲れました

BACK INTO ENGLISH

I was very tired because I dreamed that cats, dogs and mice would take the test

INTO JAPANESE

私は猫、犬、マウスがテストを受けることを夢見ていたので私はとても疲れました

BACK INTO ENGLISH

I was very tired because I dreamed that cats, dogs and mice would take the test