根据情境,选择适当句子。 1. 你向别人介这是你的朋友时,你: [ ] A. He's my friend, Li Ming. B. This is my friend, Li Ming. C. That's my friend, Li Ming. 2. 见到你很高兴,你: [ ] A. Nice to see you. B. How are you? C. How do you do? 3. 你想帮助别人时,你: [ ] A. Let you help me. B. Let me help your. C. Let me help you.