题干

一列横波在向右传播过程中,a和b两个质点在某一时刻处于如图所示的位置,其中b在平衡位置,a在最大位移处,在波的传播方向上,a、b两质点相距35cm,且大于一个波长而小于两个波长,则该波波长可能为____.

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答案(点此获取答案解析)

20cm或28cm

同类题2

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。

    A major source of teen stress is school exams,and test anxiety is not uncommon.When you recognize your teen is under stress,how can parents help your teen stay calm before an exam?

    Be involved.Parents need to be involved in their teen's work. ____ What they look for is your presence­to talk,to cry,or simply to sit with them quietly.Communicate openly with your teen.Encourage your teen to express his/her worries and fears,but don't let them focus on those fears.

    Help them get organized.____ Together,you and your teen can work out a time­table in which he/she can study for what he/she knows will be on the test.

    Provide a calm setting.Help your teen set up a quiet place to study and protect his/her privacy.Give them a nutritious diet.It's important for your teen to eat a healthy,balanced diet during exam times to focus and do his/her best.____ If this happens,encourage your teen to eat light meals or sandwiches.A healthy diet,rather than junk food,is best for reducing stress.

    ____ Persuade your teenager to get some sleep and/or do something active when she needs a real break from studying.Making time for relaxation,fun,and exercise are all important in reducing stress.Help your teen balance her time so that she will feel comfortable taking time out from studying to spend time with friends or rest.

    Show a positive attitude.____Your panic,anxiety and blame contribute to your teen's pressure.Make your teen feel accepted and valued for his/her efforts.Most importantly,reassure your teen that things will be all right,no matter what the results are.

A.A parent's attitude will dictate their teen's emotions.

B.Exam stress can make some teens lose their appetite.

C.They will only make the situation worse.

D.Encourage your teen to relax.

E.The best thing is simply to listen.

F.Help your teen think about what he/she has to study and plan accordingly.

G.Your teen may also make negative comments about themselves.

同类题3

阅读下文,回答问题

喊魂

    从我记事起,湖村人爱有意无意地跟我说:你是你爹捡的!

    他们说:那日潘河上跑水,鱼跟着泄洪道往潘河下溢,你爹拿着鱼叉在河下叉鱼。就在这时,上游漂来一只大木盆,盆中放了一个女婴,你爹当时就扔了鱼叉,鱼都顾不上要,把你抱回了家。

    这个版本初时我并不相信,我们村的大人最爱吓唬细伢时说那个谁是从哪儿哪儿捡来的。但说的人多了,说的次数多了,我忍不住问我娘:我当真是我爹捡来的不?娘听了当即怔了一下,神情很不自然,但她随即哈哈大笑起来:你个傻二丫真是捡来的呢!娘接着又说,你爹当时叉了一天的鱼,累得很,一路抱你回家时手都酸了。

    我姐大丫此时靠在门外捂嘴偷笑。

    娘见我嘴巴翘得高高的,停了笑,对我说,二丫你真个是傻丫头,我都生了你大丫姐,还捡你这丫头片子作甚?

    我立时破涕为笑。

    但大丫从此没事时老爱冲我喊:二丫,二丫,你是爹从潘河捡来的野伢子,嘻嘻……

    我很生气,几次找大丫打架,但每次都输。

    那个卖冰棒的跛子再来湖村时,我偷偷把大丫的新凉鞋提了出去。然后在大丫哭着找新凉鞋时,我伙同娟子躲在屋后吃冰棒,笑得不亦乐乎。

    娘找到我,盯着我红彤彤的嘴,又看到屋后那堆冰棒纸,脸色铁青。在她转身找扫帚时,我赶紧和娟子一起从后院门溜了。

    娟子说:二丫你别难过,我悄悄听到我娘跟人唠话时说,你爹把你捡来时,你娘哭了很久!捡了你,她就不能再生儿子了。

    我很难过。整个下午,我躲在潘河里,玩水、摸鱼……到娘找到我时,天都黑透了。

    晚上娘还没来得及揍我,我就发烧,说胡话。连着几天打针吃药都不见好转。娘整夜整夜地抱着我哭,最后在奶奶的劝说下,娘提了一大堆礼物背着我去村头找神婆“三相公”。

    娘从前不信“三相公”,一向都绕着她家走。

    “三相公”把我放在椅子上,手指头在指节上点点掐掐,最后说我被潘河中的淹水鬼缠了身,丢了魂。

    娘信以为真,就和“三相公”一起去潘河,迷迷糊糊中我听到娘的声音从潘河传来:二丫!你在潘河吓了回呀——

    迷糊中我也听到“三相公”的声音:回来了呀!

    听见娘又叫:二丫!你在潘河吓了回呀——

    唤声越来越近,娘走近我的床头,轻轻地把怀中的什么东西放在我的心口,掖紧被窝,轻拍着:我的二丫在这,我的二丫回来了喽!

    我在迷迷糊糊中,眼泪却淌湿一大片枕头。早听别人说:细伢子在野外失了魂,只有亲娘唤才能把魂魄招回来,别人喊,会把魂魄吓跑,而细伢子也就没命活了。而我,是爹从潘河上捡来的野伢子!

    潘河边又传来娘的声音,二丫!你在潘河里吓了回呀——

    那一夜,娘的沙哑的声音在潘河边来来回回响起,直到天亮,直到我迷迷糊糊睡熟。

    因为这场突 来的病,我逃过了一通海揍。但大丫从此记上我偷她凉鞋兑冰棒的仇,更频繁地冲我喊:二丫,二丫,你是爹从潘河捡来的野伢子。那天,上游漂来一只大木盆,盆中放了一个女婴,叫二丫,嘻嘻……

    我不甘示弱,也冲着她喊:大丫,大丫,你是爹从潘河捡来的野伢子。爹那天在潘河下游叉鱼,就在这时,上游漂来一只大木盆,盆中放了两个女婴,一个叫大丫,一个叫二丫,嘻嘻……

    娘在院中里听到,边作势找扫帚,边比比划划地打着手语——娘自那晚为我喊魂后,声带就拉坏了!因为娘听“三相公”说,就算不是亲娘,只要娘心在,魂魄都是能喊回来的。

(选自《大观<东京文学>》2016年01期,略有删改,作者:徐建英)

同类题4

阅读理解

    In this day and age taking a photograph is easier than ever. There are cameras built into our phones, computers, iPods…The way we share photos has also changed. There was a time when you'd print your photos and put them into photo albums, but because of the advance in technology, all in technology, all this has changed.

    Not only do we have what seems like an endless amount of space to store photos on our devices, but we also have the Internet, especially social media. Social networks such as Facebook allow us to post our pictures and albums to share friends and family.

    While you could argue this easy ability to store, share and enjoy photos is fantastic, it could also be said that photographs have lost some of their meaning. I have over 1000 pictures on my smart phone and several thousand stored on my computer. I love posting my pictures on Facebook. Sometimes, however, I try to ask myself, will I really want to look back at this picture of a coffee or a selfie taken in a bathroom by myself? Probably not.

    Even though I'm guilty about sometimes taking meaningless and boring pictures like this, a couple of years ago, I decided to find a way to make my photographs more meaningful. How did I do this? Disposable (一次性)cameras! When I go on a trip, I always try to take a disposable camera. With only 27 pictures you can take, you really think about the photograph straight away. And finally, it's so much fun to get the pictures developed and look through them again.

    I admit that I couldn't live without social media or taking photographs with my smart phone, but I do think taking photographs has become less meaningful. That's why I'll continue using disposable cameras. It's a great way to make your photographs more meaningful.