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问题 选择题

听音能辨人，主要是依据不同人的讲活声具有不同的（　　）

A．音色

B．音调

C．响度

D．振幅

答案

因为每个人的声带结构不同，所以发出声音的音色就会不同，所以我们可以通过音色辨别是谁；

故选A．

单项选择题

厅堂内有扩声时不同听众席处（）的差值成厅堂扩声声场不均匀度。

A、最大声压级

B、峰值声压级

C、稳态声压级D瞬态声压级
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单项选择题

It’s all annual back-to-school routine. One morning you wave goodbye, and that (1) evening you’re burning the late-night oil in sympathy. In the race to improve educational standards, (2) are throwing the books at kids. (3) elementary school students are complaining of homework (4) What’s a well-meaning parent to do.As hard as (5) may he, sit back and chill, experts advise. Though you’ve got to get them to do it, (6) helping too much, or even examining (7) too carefully, you may keep them (8) doing it by themselves. "I wouldn’t advise a parent to check every (9) assignment," says psychologist John Rosemond, author of Ending the Tough Homework. "There’s a (10) of appreciation for trial and error. Let your children (11) the grade they deserve. " Many experts believe parents should gently look over the work of younger children and ask them to rethink their (12) . But "you don’t want them to feel it has to be (13) ," she says.

That’s not to say parents should (14) homework-first, they should monitor how much homework their kids (15) . Thirty minutes a day in the early elementary years and an hour in (16) four, five, and six is standard, says Rosemond. For junior-high students it should be " (17) more than an hour and a half," and two for high school students. If your child (18) has more homework than this, you may want to check (19) other parents and then talk to the teacher about (20) assignments.

16（）

A.classes

B.groups

C.grades

D.terms
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