问题 选择题

某人直臂提一桶水时,这时手臂上肱二头肌和肱三头肌的状态分别是(  )

A.肱二头肌收缩,肱三头肌收缩

B.肱二头肌收缩,肱三头肌舒张

C.肱二头肌舒张,肱三头肌收缩

D.肱二头肌舒张,肱三头肌舒张

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.骨骼肌包括中间较粗的肌腹和两端较细的肌腱(乳白色),同一块骨骼肌的两端跨过关节分别固定在两块不同的骨上.骨骼肌有受刺激而收缩的特性,当骨骼肌受神经传来的兴奋刺激收缩时,就会牵动着它所附着的骨,绕着关节活动,于是躯体就产生了运动.但骨骼肌只能收缩牵拉骨而不能将骨推开,因此一个动作的完成总是由两组肌肉相互配合活动,共同完成的.

A、骨骼肌受到神经传来的兴奋刺激后,就会收缩变短,才能产生一定的拉力,骨骼肌只能收缩牵拉骨而不能将骨推开,因此一个动作的完成总是由两组肌肉相互配合活动,共同完成的,因此在直臂提水时肱二头肌和肱三头肌都处于收缩状态,符合题意.

B、在做屈肘动作时,肱二头肌收缩,肱三头肌舒张,不符合题意.

C、在做伸肘动作时,肱二头肌舒张,肱三头肌收缩,不符合题意.

D、人的双手在自然下垂时,肱二头肌和肱三头肌都处于舒张状态,不符合题意.

故选:A

单项选择题
阅读理解

I still remember --- my hands and my fingers still remember --- what used to lie in store for us on our return to school from the holidays. The trees in the school yard would be in full leaf again and the old leaves would be lying around like a muddy sea of leaves.

“Get that all swept up!” the headmaster would tell us. “I want the whole place cleaned up, at once!” There was enough work there, to last over a week. Especially since the only tools with which we were provided were our hands, our fingers, our nails. “Now see that it’s done properly, and be quick about it,” the headmaster would say to the older pupils, “or you’ll have to answer for it!”

So at an order from the older boys we would all line up like peanuts about to cut and gather in crops. If the work was not going as quickly as the headmaster expected, the big boys, instead of giving us a helping hand, used to find it simpler to beat us with branches pulled from the trees. In order to avoid these blows, we used to bribe(贿赂) the older boys with the juicy cakes we used to bring for our midday meal. And if we happened to have any money on us, the coins changed hands at once. If we did not do this, if we were afraid of going home with an empty stomach or an empty purse, the blows were redoubled. They hit us so violently and with such evil enjoyment that even a deaf and dumb person would have realized that we were being whipped so much not to make us work harder, but rather to beat us into a state of obedience(服从) in which we would be only too glad to give up our food and money.

Occasionally one of us, worn out by such calculated cruelty, would have the courage to complain to the headmaster. He would of course be very angry, but the punishment he gave the older boys was always very small --- nothing compared to what they had done to us. And the fact is that however much we complained, our situation did not improve in the slightest. Perhaps we should have let our parents know what was going on, but somehow we never dreamed of doing so; I don’t know whether it was loyalty or pride that kept us silent, but I can see now that we were foolish to keep quiet about it, for such beating were completely foreign to our nature.

小题1:The statement “my hands and my fingers still remember” (Para.1) means that___________.

A.the author’s hands were severely injured in the cleaning up

B.the author seldom did such hard work as the cleaning up

C.the author was bullied by the big boys in the cleaning up

D.the author’s hands were his only tool for the cleaning小题2:The headmaster asked the older boys to_____________.

A.beat those who worked slowly

B.treat the small boys as peanuts

C.take charge of the process of the cleaning

D.do the cleaning all by themselves小题3:According to Para. 3, if the author had any money on him, he most probably_________.

A.gave it to the big boys so as to please them

B.gave it as a bride to the headmaster

C.spent it all on his midday meal

D.spent it buying midday meals for the big boys小题4:When receiving complaints, the headmaster would deal with the big boys by means of _________.

A.slight punishment

B.strict criticism

C.complete indifference

D.good beating