题干

蓄水量为1吨的太阳能热水器现在装满了30℃的水,经过光照后升高了20℃,则水吸收的热量是____J。[c=4.2×103 J/(kg·℃)]
上一题 下一题 0.0难度 选择题 更新时间:2020-03-04 10:13:25

答案(点此获取答案解析)

8.4×107

同类题2

阅读下面的文章,完成后面小题。

我在第三棵树下等你

    ①记得中考那年,学校要求上晚自习,爸爸每天9点就到学校门口来接我。我到家他会给我加餐,有次他问我吃什么,我说要吃手擀面,我去洗漱的时候,他已经把一碗面条摆在我面前。我接过汤碗时,没想到那么热,手一抖,碗落地上了,他有点生气。我手正疼得难过,气恼地喊:“我又不是故意的!”然后一下把筷子拍在桌上,气呼呼地回了房间。

    ②第二天我放学,看见他在校门口等着我,我趁着夜色,混在同学中走过去。虽然走进胡同时,黑暗和恐惧使我的心怦怦乱跳,可我还是想让他着急,让他知道我多么重要。果然,我到家没多久,他急匆匆跑回来,我隔着房门听见他上气不接下气地问妈妈:“女儿回来没?”妈妈说:“回来一会儿了,你怎么还没接着?”他如释重负地说:“人太多了,没看清。”

    ③后来,顺着门缝飘进一张字条:“爸爸今晚在第三棵树下等你。”连个道歉也没有,倒像是约会,我把字条扔在桌子上。放学了,我缩在人群中,看见爸爸果然站在校门口的第三棵小杨树旁边,正死死地盯着校门口看,我一低头,又走了过去。快到路口的时候,我回头望望,他还在那儿身躯前探,我想他一定是在努力辨认自己的女儿。

    ④人流在减少,他依然一动不动地往前看。终于学生都走完了,只剩几个老师稀稀拉拉地走出来。爸爸赶上前去,跟他们说着什么,然后又迅速地往这边跑来,他在昏暗的路灯下追上了我,喘着粗气,隔着夜色我也能感觉到他眼中冒出火焰。他跟在我身后,一边走一边说:“你一个女孩子,自己走夜路,出了事儿可怎么办?”我自顾自地走,心里却不以为然。

    ⑤再大一点,我的所谓懂事就是学会小心翼翼地与爸爸保持和谐的距离,看人家父女拉着手走在路上,其乐融融,无话不谈,我与他却从没有过。直到上高中,我和爸爸都拧着,我要学文科,他要我学理科。我们就这样同在一个屋檐下小心翼翼又疙疙瘩瘩。

    ⑥毕业了,果然如爸爸所言,我 的专业遇冷。妈妈打电话让我回家,说爸爸给我联系好了工作。他为了我的工作甚至坐了两夜火车!

    ⑦爸爸的爱伤害了我的自尊,可我找不到拒绝的理由。因为他挑落我内心的遮羞布,让我那么自卑地蜷在角落里忧伤地感受他高大的父爱。

    ⑧好在他有妈妈陪伴,我可以堂而皇之继续躲藏。有一天妈妈给我打电话,说爸爸一天没回来。我急忙到他常去的地方找,给亲戚打电话,从我哆嗦的语音、颤抖的双腿,我终于明白我多么害怕失去他。

    ⑨一夜未睡,第二天要报警时,他回来了,我问他去了哪里。他却有些懵懂,想了想说迷路了,在公共汽车站待了一晚。带他去医院检查,医生悄悄告诉我们这是帕金森综合症的早期反应。

    ⑩他变得时而明白时而糊涂。面对他的病,我觉得自己的倔强和自尊一文不值。其实我和爸爸之间既没有隔着一堵墙,也没有不可逾越的鸿沟,只是一缕风,在彼此的爱中无足轻重的风。我难过但也感到幸运,相对那些失去后痛哭流涕的人,毕竟我还有机会挽回。就像一幅画,从那第三棵树开始涂回去,涂上更缤纷的颜色。

(文/陈柏清 有删改)

同类题4

根据短文内容,选择最佳答案。

Look into hunters' eyes

    Have you ever been face to face with a cat or a sheep? If you have,you probably noticed that cats narrow their eyes to vertical (垂直的) slits (狭缝),while sheep have horizontal pupils (瞳孔).

     Why is the difference?

    Scientists from the Universities of California Berkeley and Durham in Britain may have the answer. Their research, published recently in the journal Science Advances, suggested that pupils' shapes could tell whether an animal is a hunter or gets hunted.

    The researchers took a close look at the eyes of 214 land animals.The challenge was to see if they could find a relationship between an animal's role in the food chain and the pupils' shapes.

    They found a pattern. Species with pupils that are vertical slits are more likely to be small ambush predators (捕猎者) – creatures that lie in wait for their lunch.In contrast,those with horizontal pupils are more likely to be plant-eating prey (猎物) species.

    Evolution chose the arrangement for a good reason.For hunters such as household cats,it appears that vertical pupils not only improve their ability to keep track of moving objects like mice,but also maximize (使最大化) their ability to judge the distances of the animals they hunt.

    However, an interesting discovery from the study is that the slit pupils are mostly linked to hunters that are close to the ground. Therefore, bigger cats who actively hunt down their prey, like tigers and lions, don't have slit pupils.

    On the other hand, for plant-eating prey animals, horizontal pupils give them a wider field of vision.When stretched (伸展) horizontally,the pupils allow for more light to enter from the front, back, and sides. Meanwhile, they also limit the amount of light from the sun above so the animal can see the ground better.“ Once they do find a predator,they need to see where they are running,” said leading researcher Martin Banks,a UC Berkeley professor of optometry (视光学).“They have to see well enough out of the corner of their eye to run quickly and jump over things.”

    But what happens when they bend down to eat? Researchers checked this by watching prey animals in the Oakland Zoo in California, US. They believe that when goats lower their heads to eat,their eyes rotate (旋转) to keep their pupils horizontal.

    So it seems that the eyes are indeed the window to the soul!