学校联欢会上，李欣同学表演了小提琴独奏．琴弦振动产生的琴声，_爱下问搜题

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问题填空题

学校联欢会上，李欣同学表演了小提琴独奏．琴弦振动产生的琴声，通过______传到大家耳里，琴声是以______的形式传播的．

答案

琴弦振动产生的琴声，是通过空气传到人耳中的；琴声是以声波的形式向外传播的．

故答案为：空气；声波．

选择题

给出下列四个命题：
①若ξ～B（4，0.25），则Eξ=1
②线性相关系数r的绝对值越接近于1，表明两个随机变量线性相关性越强；
③若a，b∈[0，1]，则不等式a²+b²≤1成立的概率是

；
④函数y=log2(x2-ax+2)在[2，+∞)上恒为正，则实数a的取值范围是(-∞，

)．
其中真命题个数是（　　）

完形填空

It happened towards evening, when I was resting in a cafe. I 36 a pair of newly bought white leather shoes, which were rather expensive. Then 37 came to me.
He was in an unfit shirt, 38 pale and weak. He looked about eleven or twelve. No sooner39 begun to speak than he opened the box in his hand and took out the tools of shoe-polishing. He bent down, 40 my leather shoes, and began to shine them.
He was concentrating on his job when heavy rain began to pour 41 . People rushed into the cafe for protection from the 42 . More and more people crowded in and gradually 43 the boy from me.
Hours passed, and 44 turned dark. I had no shoes on my feet and wondered 45 the boy had been. I thought he would not 46 my leather shoes, and I would have to walk back home on 47 in the night.
When it was near midnight the rain 48 , people started to go out. The cafe 49
Closed. I had to move to the door, I was surprised to see the boy sleeping on the floor with his head leaning 50 a box. He held a package made of his shirt tightly in his arms.
I 51 him slightly and woke him up. He jumped up and rubbed his eyes for a while before he 52 me. Then he opened the 53 hurriedly, gave me my leather shoes, and apologized to me shyly.
I paid him and wrapped around him his unfit shirt, which 54 my leather shoes.
After saying goodbye to the boy, I was 55 home, with the image of the boy staying in my mind.

C．my bare feet

D．my own foot

A．was wrapping

B．was wrapped

C．had wrapped

A．on the way to