完成句子，使改写后的句子完整，并与原句意思相符，注意每空只填一个单词。
1. What’s your last name?
What’s your ________ ________?
2. Can I help you?.
______ can I _______ for you?
3. Thank you for your letter.
_________ for _______ a letter to me.
4. How much are the pants?
_______ __________ ________ ________ these pants?
5. He often helps me with English.
He often helps me ______ _________.