问题
单项选择题
决定超声波在界面上的相对透过率和反射率的是（）
A、声衰减
B、声速
C、声阻抗比
D、声频率
答案
参考答案：C
搜题请搜索小程序“爱下问搜题”
决定超声波在界面上的相对透过率和反射率的是（）
A、声衰减
B、声速
C、声阻抗比
D、声频率
参考答案：C
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| On Sundays we often go to the 1____________ near our city. There are many 2____________ in it-tigers, elephants, pandas and monkeys. The 3____________ are very big. They all have 4____________ noses. Their noses can 5____________ them eat and drink. Tigers are very 6____________. They often run about. They don't like to 7____________ in the zoo. Many people like 8____________. They are animals of China. But I like monkeys most (最). We like 9____________ to the zoo. We can 10____________ more (更多) about animals there.
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