轻敲西瓜来判断成熟程度,这是利用了声音的【 】
A.响度
B.音调
C.音色
D.声速
答案:C
题目分析:音色是由发声体的材料和结构决定的,生熟西瓜相比,内部结构不同,所以音色不同。
x
1
2
3
f(x)
6.1
2.9
-3.5
根据句意或首字母填空,每空一词。
1. The boy is a h_______ school student. He studies at Green H_______ S_______.
2. Some students exercise once _______ twice a week.
3. M_______ students in our class do homework every day, but some students often copy
others' homework.
4. I was surprised at the r_______ of the basketball game.
5. The students in our school take an _______ part in club (社团) activities.
6. As _______ housework, Mrs Liu hardly ever does it.
7. The results _______ "watch TV" are interesting.
8. I go skateboarding a_______ twice a week.
9. He is an a_______ boy in class.
10. I do my homework five _______ a week.