употребите вопросы в косвенной речи.помогите, пожалуйста:)

He doesn't know who the nineteenth president of the United States was.  He isn't sure when the Civil War ended. He doesn't remember when California became a state.  He has forgotten where George Washington was born.  He can't remember how many people the Declaration of Independence signed.  He doesn't know where Abraham Lincoln was assassinated. He has forgotten why Washington was chosen as the capital.He has no idea  what Alexander Graham Bell invented.