题干

如图是一个饮水壶的部分结构示意图,a、b是出水管的两端,壶内水面低于出水管的a端,活塞与壶口接触紧密且能自由移动。用力F向下压活塞,在水从a端匀速流出来(壶内水面始终高于b端)的过程中,壶内气体的温度保持不变。则(  )

A:壶内气体的压强大小不变

B:壶内气体的体积逐渐变小

C:向下压活塞的力F逐渐变大

D:壶底内表面所受的压力大小不变

上一题 下一题 0.0难度 选择题 更新时间:2019-05-08 06:39:18

答案(点此获取答案解析)

B,C,D

同类题2

完型填空

    Once again, I had run away and really did not know why. I walked out of the gate to go to school and then kept 1. I had just turned eleven years old the week before. It was almost dark; I was tired, scared, cold, and all alone. I had not eaten all day and was afraid to turn 2 into the police.

    As darkness fell, I made my way over to the city park 3 on Park Street. I entered the darkened area and sat down on one of the wooden benches.“Well, hello, young man.” A voice came from 4 me. I jumped, almost falling off the park bench. I could feel my heart beating in the side of my neck. I could 5 catch my breath. I looked back and saw a woman standing behind me in the shadows. She found I was 6 because of feeling cold, so she took off her large scarf and covered it 7 my shoulders. Looking into my eyes, she8 me if I need something to eat. After I said “yes”, she held out her hand and told me to take the very letter 9 I was unable to see to the store owner. I looked at her outstretched arm but saw 10 in her hand. However, I 11 my hands slowly, acting as though I was taking something from her hand.

    I came to a store with a 12 sitting behind a counter. I opened the door, very slowly I held out my hand which has nothing in it toward her. I watched her face to see if she might think I was crazy or something else.13, she immediately turned and walked to the back of the store for the food I need. After that, I walked out into the street and headed back to the park where the old woman was. “Can I have the letter so I can be magic too?” I asked. Without replying to me,14 she told me the persons who wanted to help15in need would never need the magic letter any more. With these words, she stood up, kissed me on the forehead, removed the large scarf from my shoulders and disappeared into the darkness.