问题 选择题

某人的肘弯曲时,他相关的骨骼肌应该处于的状态是(  )

①肱二头肌收缩   ②肱二头肌舒张  ③肱三头肌收缩   ④肱三头肌舒张.

A.①④

B.②③

C.①③

D.②④

答案

骨的位置的变化产生运动,但是骨本身是不能运动的.骨的运动要靠骨骼肌的牵拉.骨骼肌中间较粗的部分叫肌腹,两端较细的呈乳白色的部分叫肌腱.肌腱可绕过关节连在不同的骨上.骨骼肌有受刺激而收缩的特性,当骨骼肌受神经传来的刺激收缩时,就会牵动骨绕着关节活动,于是躯体就会产生运动.但骨骼肌只能收缩牵拉骨而不能推开骨,因此与骨相连的肌肉总是由两组肌肉相互配合活动的.屈肘时,肱二头肌收缩,肱三头肌舒张;伸肘时,肱二头肌舒张,肱三头肌收缩;双手竖直向上提起重物或双手抓住单杠身体自然下垂,肱二头肌和肱三头肌都收缩;双臂自然下垂,肱二头肌和肱三头肌都舒张.可见,选项A符合题意.

故选:A.

阅读理解与欣赏
阅读理解

What did you dream about last night? Did your teeth fall out or did you fly? Maybe you died or someone you know did.Or maybe you were back in high school.These are among the most common dreams people have and they all mean something.Here are some of the most common dreams and their interpretations or symbolism.

Dreams of flying.Dreams of flying represent feelings of freedom that may result from an instance when you overcome a limitation or obstacle.Usually, children have more flying dreams than adults, because children are more open to their possibilities, and adults have often accepted limitations imposed by society.

Teeth falling out.Food in a dream is symbolic of knowledge because food nourishes the physical body and knowledge nourishes the soul.Teeth are a means to break down food or knowledge.When your teeth fall out in a dream, it could signify that you feel ill - equipped to break down the knowledge that you have available, that the way you break things down has changed.That change can be either positive or negative.

High school dreams.High school is a place of learning from the past, and dreaming of being unprepared for a high school test can indicate a struggle to access information you need to handle in your life.

Recurring dreams and nightmares.Recurring dreams are your subconscious (潜意识)mind's way of trying to get your attention.A recurring dream is a step down from a nightmare that is a louder, more insistent way your subconscious mind communicates.If you have a recurring dream, try to stop in the dream and identify what the dream is trying to tell you.That could mean asking someone who is chasing you what he or she wants.A woman dreamed for years that an old, haggard woman was chasing her around her home.When she finally stopped in the dream and asked the old woman what she represented, the old woman suddenly turned into a beautiful young woman and replied, "I represent your question of ' what if?’ "

小题1:The text is mainly about ____.

A.high school dreams

B.dreams' symbolism

C.dreams of flying

D.nightmares小题2:After you' ve got out of some difficulties, you might have a ____.

A.high school dream

B.dream of flying

C.dream of teeth falling out

D.a nightmare小题3:If you dream of being unprepared for a "high school test, it means____.

A.you' re trying to learn something

B.you will certainly fail in the test

C.you will be scolded by your teacher

D.you' re not well prepared for the test小题4:The underlined word "identify" in the last paragraph most probably means____.

A.break out

B.recall

C.make out

D.explain小题5:The woman' s dream is mentioned mainly to ____.

A.tell us nothing but an interesting story

B.show us what a nightmare is like

C.tell us that women are always changeable

D.show us the way to deal with a recurring dream