问题
单项选择题
下列哪一项不影响回波反射强度（）。
A.声束入射角度
B.界面
C.声阻抗差
D.声波速度
答案
参考答案：E
搜题请搜索小程序“爱下问搜题”
下列哪一项不影响回波反射强度（）。
A.声束入射角度
B.界面
C.声阻抗差
D.声波速度
参考答案：E
| 补全对话，从方框中选择合适的句子补全对话。 | |
| A: Mary, tomorrow is your Mum's 50 th birthday, do you know? B: Of course I do. 1 A: First of all (首先), a birthday present. 2 B: That's a good idea. It'll make her look young. And a big birthday cake, too, with 50 candles. A: 3 Will we have a special dinner? B: 4 A: Fine, where will we have it? B: Dad, we can have it at home and cook Chinese food for my mother. I'm sure Mum will like them. A: All right. Will you do some shopping too? B: 5 A: OK. | |
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