人的上臂以肩关节为枢纽，可做伸屈、旋转、换转等各种动作．这说_爱下问搜题

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问题选择题

人的上臂以肩关节为枢纽，可做伸屈、旋转、换转等各种动作．这说明关节在运动中起什么作用（　　）

A．动力作用

B．杠杆作用

C．支点作用

D．调节作用

答案

关节是指骨与骨之间能够活动的连接，由关节面、关节囊和关节腔三部分组成．

关节面包括关节头和关节窝．关节面上覆盖一层表面光滑的关节软骨，可减少运动时两骨间关节面的摩擦和缓冲运动时的震动．

关节囊由结缔组织构成，包绕着整个关节，把相邻的两骨牢固地联系起来．囊壁的内表面能分泌滑液．在关节囊及囊里面和外面还有很多韧带，使两骨的连接更加牢固．

关节腔由关节囊和关节面共同围成的密闭腔隙，内有少量滑液．滑液有润滑关节软骨的作用，可以减少骨与骨之间的摩擦，使关节的运动灵活自如．

运动中，关节起着支点的作用（也有说枢纽作用）．

故选：C

选择题

化学反应往往需要在一定条件下进行．通过控制或改变反应条件，可以加快、减缓甚至阻止反应的进行．如图所反映的措施中，能加快其化学反应速率的是[ ]

A．铁门表面喷漆

B．冰箱保存食物

C．扇子扇煤炉火

D．烤焦的电线杆底部

完形填空

As a music teacher，I have always known that music touches the soul. It can 36 all kinds of barriers to reach students in a very special way.It can be the 37 for each child to find their light.I would like to 38 a story about it.
For a few years I was 39 with the opportunity to teach disabled students.One of my most 40 students was a five-year-old girl called Vanessa，who had difficulty walking，and could not speak.We 41 sat on the floor for our music lessons and Vanessa liked to 42 on my lap．One of her favorite songs was John the Rabbit.It was a call and response song where I sang the call and the students 43 twice while singing the repeating phrase，“Oh，yes！” Vanessa liked to 44 her hands together with mine and clap with me.We probably performed that song during every class，Vanessa and I clapping together.But she 45 said or sang a word.
One day，when the song was finished，Vanessa turned around， 46 me in the eyes，clapped her tiny hands twice and said the words“Oh，yes！” I opened my mouth in 47 and for that moment I was the one who could not speak.When my heart 48 started beating again，I looked over at the assistant teacher to find her also 49 .Through music，we had made an awesome connection.
Several years later，I met Vanessa on the street in town.She waved with a big 50 on her face and then clapped her hands twice，imitating the song we had 51 so many times in our music class.The little girl， 52 her connection with music，left an impression on me that will last forever. Every child has the 53 to learn and grow. It is up to us to 54 the way to reach each and every one of our students.We all must find each child's 55 .

D．break through

A．troublesome

B．Hardworking

C．astonishment

D．embarrassment

A．immediately

B．fortunately