问题 问答题 简答题

何谓被囊类、无头类、原索动物、有头类、无颌类、有颌类、无羊膜动物和羊膜动物?

答案

参考答案:

被囊类:尾索动物亚门的动物体表有被囊,故将其又称为被囊类。

无头类:头索动物亚门的动物头部不明显,故称为无头类。

原索动物:把尾索动物亚门和头索动物亚门合称为原索动物,有原始的脊索动物的含义。

有头类:脊椎动物亚门的动物均有明显的头部,故又称为有头类。

无颌类:原口纲的动物有头,但无上下颌,故又称为无颌类。

有颌类:有头且有上下颌的动物合称有颌类,它包括鱼纲、两栖纲、爬行纲、鸟纲和哺乳纲。

无羊膜动物:指胚胎发育中不出现羊膜的所有脊索动物的统称。它包括除爬行纲、鸟纲和哺乳纲以外的所有脊索动物。

羊膜动物:指胚胎发育中出现羊膜的所有脊索动物的统称。它包括爬行纲、鸟纲和哺乳纲。

完形填空

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

Improve your memory, improve your life

Mark began to introduce the guest speaker to the audience, but then he paused in horror. _________

Barbara hid her jewelry when she went on vacation. When she came back, she couldn’t remember where she’d put it.

__________. Most people have. But memory can be developed.

First, relax. If you’re overanxious about remembering something, you’ll forget it. ________.Take a deep breath and tell yourself that you have all the time in the world to remember.

Second, avoid being negative. If you keep telling yourself that your memory is bad, your mind will come to believe it and you won’t remember things. When you forget something, don’t say, “ Gee, I need to have my brain rewired(重装电线).”

To improve your memory, you’ll need to take an active role. Like your body, your memory can be strengthened through exercise. ______ For example, if you’ re learning a language, try to actively remember irregular verbs.

You may also want to make associations, or links, between what you’re trying to remember and things you already know. For example, if you need to catch a plane at 2:00pm, you can imagine a plane in your mind and notice that it has two wings. ___________.  

A.Don’t worry.

B.He had forgotten her name.

C.Perhaps you’ve had experiences like these.

D.Look for opportunities to exercise your memory.E. Jokes like this will have a negative effect on your memory.

F. You are now ten times more likely to remember the take-off time.

G. Relaxing will help improve your awareness and ability to concentrate.

单项选择题