题干

通过呼吸运动,肺实现了与外界环境的气体交换.下列关于平静呼吸的表示,正确的是(  )


A:胸廓扩大→肺扩张→肺内气压>大气压→气体入肺

B:胸廓缩小→肺回缩→肺内气压<大气压→气体出肺

C:胸廓扩大→肺扩张→肺内气压<大气压→气体入肺

D:胸廓缩小→肺回缩→肺内气压>大气压→气体入肺

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答案(点此获取答案解析)

C

同类题1

阅读下面材料,在空白处填入适当的内容(1个单词)或括号内单词的正确形式。

           We're human, and it's not always easy to get along with everyone all the time.Sometimes we hurt other people's feelings without intending to. Sometimes,we're ____(deliberate) mean and we feel bad afterward. So we apologize. Apologies are one of the tools we use to build good friendships andrelationships. ____ you say“I'm sorry” (and really mean it), it's because youprobably feel bad that something you did or said hurt the other person. Sayingyou're sorry is more than just words. You're also saying that you respect theother person  ____  you care about his or her feelings.Apologizing shows you have empathy.

     After  apologizing,you might feel alittle ____(good).The other personprobably will, too. When you apologize in a caring way, you can feel goodbecause you are trying to make things right again.

     Some times a heartfelt“I'm sorry” ____(fix) everything right away. Other times,it might take  ____while for someone to get past feeling upset. You may need to give the otherperson some time. Even after you say you're sorry, you might still feel bad aboutwhat you said or did—but you can feel good about apologizing, fixing themistake, or making up your ____ to do better. When someone apologizes to you,you may welcome it and be ready to forgive  ____ happened and move on. Or you might not feel like being friendly againright away. If a person keeps hurting you and ____ (apologize)without making aneffort to change,you might not want tohang about ____  that person any more.

同类题5

阅读《飞到天上去发电》,回答问题.

被称为“蓝天白煤”的风能,是一种取之不尽用之不竭的可再生能源,人类很早就开始利用风能,但以前只是将它用于航行、抽水、磨面,直到19世纪末,丹麦才建成全球第一个风力发电装置.风力发电的原理是利用风力带动风轮叶片旋转,经过增速机提高转速后驱动发电机发电.只要风速超过3m/s的风就可以用来发电.

风力发电所需要的全套装置,由风轮、发电机和铁塔3部分组成,如图甲所示.铁塔是支撑风轮和发电机的构架,一般建得比较高,目的是获得比较大且比较稳定的风力.在地面上,由于受到地形的影响或建筑物的阻挡,风速会不断波动.但是在三四百米的高空,风速不仅稳定,而且也比地面上大好多倍,可是,风力发电的铁塔不可能建得那么高,有没有什么办法让风力发电机飞到高空去发电呢?

2012年,美国阿尔泰罗能源公司研制出一种可以漂浮在空中的风力发电机,如图乙所示.这种发电机是普通发电机与飞艇的组合.它有一个充满氦气的圆筒形塑料外壳,用来提供升力,外壳的中间是一台普通的风力发电机,由绳索和电缆与地面连接,通过电缆将电传输到地面.它能够在距地面约100米的高度发电,如图乙所示,使用同型号的发电机,它的发电效率是传统风力发电机的2倍.商业用高度可达到约300米,这一高度的风力更强,也更为稳定.发电机工作时利用高空强风发电,风力可达到传统风力塔的5倍.

这款风力发电机可用在偏远地区的工业和军事设施上.它的噪音小,不会对环境造成不利影响.由于他的升降不需要借助起重机,所以装配整套设备只需要几天时间,维护起来也非常方便.

(1)风力发电机把风的____ 能转化为____ 能.

(2)请你写出漂浮在空中的风力发电机的两项优点:

____ 

____