问题 选择题

人一生发育最晚的器官是(  )

A.脑

B.心脏

C.肾脏

D.生殖器官

答案

有题意可知,人体发育过程中,各器官、系统的发育是有一定次序的,其中最早发育的是神经系统,胎儿的大脑发育是在妊娠的第四周就开始了,一直到出生,他(她)的神经细胞是在不断的分化和形成,6-7岁接近成人水平,几近成熟.期间消化系统、循环系统、泌尿系统等相继发育,直至成熟.最晚发育成熟的是生殖系统,生殖系统的发育从青春期开始,在青春期阶段,随着神经、内分泌系统的成熟,生殖器官开始迅速发育,表现为性发育和性成熟,男性的睾丸和女性的卵巢都重量增加,并能够产生生殖细胞和分泌性激素,性激素能促进第二性征的出现,女孩开始出现月经,男孩出现遗精.

故选:D

阅读理解

阅读理解。

     My teenage son Karl became withdrawn after his father died. As a single parent. I tried to do my best

to talk to him. But the more I tried, the more he pulled away. When his report card arrived during his junior

year, it said that he had been absent 95 times from classes and had six falling grades for the year. At this

rate he would never graduate. I sent him to the school adviser, and I even begged him. Nothing worked.

     One night I felt so powerless that I got down on my knees and pleaded for help. "Please God, I can't do

anything more for my son. I'm at the end of my rope. I'm giving the whole thing up to you."

     I was at work when I got a phone call. A man introduced himself as the headmaster. "I want to talk to

you about Karl's absences." Before he could say another word, I choked up and all my disappointment and

sadness over Karl came pouring out into the ears of this stranger. "I love my son but I just don't know what

to do. I've tried everything to get Karl to go back to school and nothing has worked. It's out of my hands."

For a moment there was silence on the other end of the line. The headmaster seriously said, "Thank you for

your time", and hung up.

      Karl's next report card showed a marked improvement in his grades. Finally,  he even made the honor

roll. In his fourth year, I attended a parent-teacher meeting with Karl. I noticed that his teachers were

astonished at the way he had turned himself around. On our way home, he said, "Mum, remember that call

from the headmaster last year?" I nodded. "That was me. I thought I'd play a joke but when I heard what you

said, it really hit me how much I was hurting you. That's when I knew I had to make you proud."

1. By saying "Karl became withdrawn", the author means that the boy changed entirely and _____.

A. preferred to stay alone at home

B. lost interest in his studies

C. refused to talk to others

D. began to dislike his mother

2. There was silence on the other end of the line because _____.

A. the speaker was too moved to say anything to the mother

B. the speaker waited for the mother to finish speaking

C. the speaker didn't want the mother to recognize his voice

D. the speaker was unable to interrupt the mother

3. The sentence"…he even made the honor roll" means that"_____ ".

A. he was even on the list to be praised at the parent-teacher meeting

B. he was even on the list of students who made progress in grades

C. he was even on the list of students who had turned themselves around

D. he was even on the list of the best students at school

4. What is the main idea of this passage?

A. Children in single-parent families often have mental problems.

B. Mother's love plays an important role in teenagers' life.

C. Being understood by parents is very important to teenagers.

D. School education doesn't work without full support from parents.

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