题目

用适当的句子补全对话 A: Hello! May I speak to Helen, please? B: Sorry, _____________1______________. Who’s that? A: Oh, this is Peter speaking. Is that Mrs. Black? B: Yes. A: You know I’ve got something important to tell her. _______2_________ B: Certainly. A: Please tell her the students in our class are going to plant trees this Saturday. B :_______________3________________? A: We’ll meet at the school gate at half past seven that morning. B:_____________4________________? A: No, that’s all. Thank you, Mrs. Black. B: _____________5_______________. Bye. A: Bye.发声体振动的快慢决定了:A.声音的响度;　 B.声音的音色;　 C.声音的音调;　 D.声音的大小.