根据对话语境，在每个空白处填入一个适当的句子，使对话完整通顺。
LIN TAO: Hello, may I speak to David?
DAVID: 1________!
LIN TAO: Hi, David! 2________.
DAVID: Hi, Lin Tao. What can I do for you?
LIN TAO: 3________.
DAVID: Homework?
LIN TAO: Yes. 4________. Could you tell me what Mr. Li asked us to do?
DAVID: OK. He asked us to do Exercise 2 on page 56.
LIN TAO: OK. Thanks a lot.
DAVID: 5________. Bye!
LIN TAO: Bye!
