1道英语题目说明理由
1.He joined the army when he was fifteen.(保持原句意思)
He joined the army _______ _______ _______ _______ fifteen.
2.I'm 20 years old.Peter is 22 years old.(两句并一句)
I'm _______ _______ than Peter.
3.Tom and Mark are good at maths.
______ Tom and Mark ______ ______ in maths.
请说明理由.