题干

下列属于变态发育的是(  )

①蝌蚪发育成青蛙  ②“毛毛虫”发育成蝴蝶  ③蚕幼虫发育成蚕蛾  ④雏鸡发育成大公鸡.

A:①②③

B:①②④

C:②③④

D:①③④

上一题 下一题 0.0难度 选择题 更新时间:2019-11-21 03:10:32

答案(点此获取答案解析)

A

同类题3

阅读下面短文,根据短文内容完成表格中所缺信息,每空一词。   

    Some students, parents and teachers in Shanghai were surveyed last month. According to the result of the survey, the generation gap (代沟) between students and parents as well as teachers is becoming wider. Here is what they said.

    Voice of the students:

    "Our parents hold too high expectations(期待)which put us under lots of pressure(压力). They care too much about our lives and studies," one student said.

    "It's impolite that some students' parents read their children's diaries without permission!" one student said angrily.

    "Some of our teachers are so serious that we can't make friends with them at all," another student said sadly.

    Voice of the parents:

    One mother said, "After school, my daughter usually locks herself into her room and spends lots of time talking with others on the phone. And I can't stand her clothes and hairstyle!"

    "I thought my son was doing very well in his studies. I didn't realize I was being cheated (欺骗) by him until I got a call from his teacher," said a father.

    Voice of the teachers:

    An English teacher said, "Today, the role of the teacher is to put knowledge into students' brain. The power teachers have kept students away from them."

    "Some parents pay too much attention to their children's grades. They never create a lively and colorful environment at home," another teacher said.

    "In the past, teachers and students often played games together or talked with each other. Today, only studies and grades are talked about," said a teacher.

    Voice of scientists:

    Scientists say that a school should be a place where students can learn not only knowledge, but also how to face failure bravely enough.

The generation gap (代沟) ____ students and parents as well as teachers

Voice of the students

● Parents expect us too much and ____ too much about our lives and studies.

● It's not ____ of our parents to read our diaries without permission.

● Some of our teachers are so ____ that we can't make friends with them at all.

Voice of the ____ 

● Some children keep themselves ____ in their own rooms and only chat with others on the phone after school.

● Some children ____ us until we get a call from the teachers.

● We can't stand their clothes and hairstyle.

Voice of the teachers

● The power teachers have kept students away from them.

● Some parents pay too much attention to their children's grades instead of ____ a lively and colorful environment at home.

● We ____ to play games together with our students or talk with each other. Today, only studies and grades are talked about.

Voice of scientists

● At school students should not only learn knowledge, but also learn to be ____ when they face failure.

同类题5

阅读下面《美丽的坏蛋》节选,完成后面问题。
        ①犹如一朵鲜花那样绽放的海星竟然是凶狠的动物,而且还是贪婪的食肉动物,真是令人不可思议。海星全身布满了“现代化武器”,在显微镜下,能看到它身体表面簇拥着成千上万的聚光性质小晶体。而每一个晶体都能发挥眼睛的功能,四面八方的环境可以同时“视察和掌控”,其“浑身都是监视器”。海星还有成千上万条比牙签还细的管状腿,具有强力的吸附功能,在海星大脑司令部的统一指挥下,这成千上万条腿有节奏地迈动,可以爬过所有的坎坷,即使在光滑直立的礁石壁上,也照样稳步前行。更可怕的是海星能分泌高能量的消化酶,不亚于人类生产出来的硝酸,坚硬的贝壳在这种酶作用下,很快就被腐蚀溶解,束手就擒。
        ②海星所到之处,一片恐慌。扇贝摆动两叶,贝壳急急逃走,海胆张开所有的针刺顽强抵抗,海参吓得在沙滩上打着滚儿逃离,一些海螺由于过度惊恐,竟迸发出旋转壳体的奇能,妄图从海星阴险的拥抱中逃命。有时连螃蟹也成了海星的俘虏,被海星吸食殆尽之后,只剩下精制标本一样的螃蟹骨骼。海星全然像一支偷袭的军团,有目标有计划地向贝类的藏身处前进和包抄,然后来个密集型进攻,大片的贝类群体被洗劫一空。
        ③这么美丽的东西竟是残酷的杀手,人们气疯了,他们把捕捉到的海星用渔刀渔叉奋力地砍杀,然后将海星碎块抛进大海里。人们以为自己胜利了,实际上他们犯了个大错误,海星还具有一种更特殊的能力,就是每一个碎片都可以再生一个海星。更令人不可思议的是,海星只有在卵化状态时,会被一些鱼类捕食,可一旦长成海星,几乎就没有天敌。问题是吃海星卵子的鱼类,大部分已经被人类捕捞光了,所以海星就放心大胆地娶亲生崽,发展壮大起来。
        ④仅从一些报道中,就可以看到海星给人类造成了多么可怕的灾难。近些年来,山东半岛和辽东半岛的海域,因海星灾害导致鲍鱼、扇贝和蛤蜊的养殖损失达数万亿元;山东胶州湾一家养殖公司16万亩滩涂的蛤蜊,遭到海星的大举进攻,80%的蛤蜊被吞噬;辽宁庄河市黄海沿岸成千上万吨的鲍鱼、海参、蛤蜊被海星吃掉。据调查,一个海星一天能吃掉十几只扇贝,食量惊人,再加上养殖的贝类无法自由逃走,所以沿海的一些养殖区里的贝类全部被海星吃光,几乎是养殖业的灭顶之灾。                         (选自《青年博览》)