题干

下面的几种现象中,属于可遗传变异的是(    )

A:人种的皮肤有黑、白、黄之分

B:阳光充足处比树荫下小麦穗大

C:黄种人在热带生活两年皮肤变黑

D:笼中养大的老虎不善于抓捕活猎物

上一题 下一题 0.0难度 选择题 更新时间:2017-11-25 11:03:31

答案(点此获取答案解析)

A

同类题2

阅读下面短文,从短文后各题所给的四个选项(A、B、C和D)中选出可以填入空白处的最佳选项。

    Many years ago, when we first went to Canada, we were driving through Montana to Colorado with our two children, then aged 8 and 11. As it was getting1we started looking for a hotel, only to find out that it was

    2time in that part of the country, and all the hotels were3.

Finally, around 9 o'clock in the evening, we 4 at a gas station to fill up on gas. My husband asked for a

    5 book and told the woman at the counter that we were trying to find a hotel. She told us it would be 6. He tried for 15 more minutes. When he was 7, the woman, Linda, said she and her family

     8 nearby and would be happy if we spent the night at her home.

My husband was 9 at her offer of generosity (慷慨). She called her son to10us, since she had to

    11 at the gas station till midnight.

    When we reached their home, her husband12 us. He invited us to have coffee and chat while we 13 his wife. She came past 12 am. We asked if we could slip away in the morning so as not to14 them. They said we were now 15 and we would have to have breakfast with them.

    Next morning, we ate breakfast, and when we were 16, my husband asked if he could offer some17. They would not hear of it and18we were their guests. We kept in touch for many years, and invited them to our19, too. Over the years, we lost touch, but have 20 forgotten their kindness.

同类题4

阅读秦文君的《红书包》,完成后面小题。
①很多人说“三岁看大”,可是我分明感觉孩子的秉性和悟性是由着成长来雕琢的,时时都存在着改变的可能。
②距离现在很多年前,我还是个小学四年级学生,和那个年龄的女孩一样,长着一头柔软的黄头发,扎着可笑的小辫子,并不知道自己最想要的是什么,好像女孩子的天性已经萌生,有一阵格外要美,挺注意同龄女孩穿些什么,看上后就会迷迷糊糊的,想像自己拥有它们后的模样。看见好朋友打了个淡绿色的蝴蝶结,过不了几天,非要缠着母亲也替我买一副相同的蝴蝶结,结果两个人走在路上被人误以为是双胞胎。这样的事情发生得太多了,多得都让家人感到习以为常了。
③有一回,同班的女孩背了一只崭新的红书包,那书包简直美极了。我只看它一眼,心里就发颤,不由伸出手去摸一摸,大概它美到我心里去了。
④记得那天天气很干燥,我不知道喝了多少水却还是在喝,注意力被这美丽的红书包缠绕着,扭过脸一遍一遍地看它,别的一切感受都退得远远的,仿佛快活与否,就同这书包紧密地连在了一起。那天放学时,女孩就走在我的前面,我跟着走,听着大伙都在议论她的书包漂亮,原来人人都看出了它的好,被这种认同感影响着,一个念头从我心里升了起来:我一定要马上拥有一只这样的书包。
⑤一连几天,只要一放学,我就去街上寻找,专跑文具店。终于,我在一家小文具店的橱窗里找到了这样的红书包。隔了层光闪闪的橱窗玻璃,我发现它更加吸引人了。我在它跟前站了许久,一会儿凑近着看,一会儿退远点看,过一会儿又捂上一只眼,单眼看。“没有什么能同它比美。”真的,当时我就那么想,“它是我最想要的。”
⑥我又奔又跑地赶到车站,等了三部公共汽车,才等到母亲从车上下来。她惊讶地看着我,我什么也不说,拉着她的手直奔那家文具店。到了那儿,就指着红书包说:“请给我买吧,妈妈。”
⑦“可你的书包还挺新的,而且也很漂亮。”
⑧我不知怎的就想哭,一边死活不肯离开,像是打算在这儿站一辈子。母亲摸摸我发烫的额头,心就软了。没想到她摸出钱夹要付钱时,才发觉带的钱不够。可在这时,店要打烊了。
⑨夜里,我老做梦,梦见店里的红书包让人用一把大剪刀剪坏了,急得我大嚷大叫起来。父亲把我唤醒,小声对我说,明天,他下了班就去把我的红书包买回来。
⑩第二天的整个白天,我都非常快乐,心里涌动着紧张和激动。见了那个背红书包的女孩,我对她微笑了,心里充满模糊的好感:我马上就可以背上那只红书包,同她的一样。到了傍晚,我突然变得惴惴不安:万一那店里的书包都让别人买去了呢!于是,我三番五次往那里跑,弄得店里人都开始皱起眉头来打量我。
⑪晚上,爸爸推着自行车,一手高高举着红书包回来了。我抢过那只鲜红的书包,高兴得打转。等狂喜过之后,才看见母亲正在给父亲搽松节油。原来,为了快点赶到店里,父亲骑车时同一部黄鱼车撞在一起,膝盖上肿起老大一块。
⑫我的心情沉重起来:我怎么会不顾一切地迷上这红书包的,竟没发现父亲的膝盖为了它受伤了呢。
⑬父亲说:“爱美是件好事,可生活中美的东西太多了,跟着去争,永远也是跟不过来的,能体会美才是最美的事情。”
⑭第二天,我背着红书包兴高采烈地去学校,在校门口碰见那个女孩。谁知她又换了个紫色的新款书包,比原来的红书包漂亮不知多少倍。
⑮从那天起,我依然爱一切美丽,美的旖旎永远能给予我无限的灵感,可是从此就没有再像过去那样焦躁不安了,看开了很多,能懂得美的东西美在何处有时就很知足了,也很快乐,世界上最美的东西莫过于存着的爱美的心。
⑯那个红书包用旧后,我像宝贝一样珍藏了好多年。不为别的,就因为它已经成了我童年生活的一个启示录