题干

有关卵子的发生叙述不正确的是(   )

A:卵原细胞通过有丝分裂的方式增加数量

B:初级卵母细胞在胎儿期形成

C:减数第一次分裂均在排卵前完成

D:卵子在输卵管中受精

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答案(点此获取答案解析)

C

同类题3

阅读下文,回答相关问题

                                                                                                 刷鞋匠的绝招   曾颖
        公共汽车的门开了,一大群赶着上班的人和挑着担子背着包袱的外地小商贩蜂拥着挤上车来,投币声和刷卡声滴滴嗒嗒响成一片。毫无感情色彩的电子人机械地重复着:本车为无人售票车,请自觉刷卡或投币……
        该上的上完了,关车门。司机冲一个小个子乡下人喊:请自觉投币!
        小个子的乡下人理了理肩上挎的小木箱,把手中的木凳往地上一放,坐下,很反感地盯了一眼司机,想说什么,但忍住了。从他衣服上闪闪发光的黑色油痕和他随身携带的板凳和木箱我们看得出,他是一个刷鞋匠。
       司机并没因他的反感而放过他,嘴里又说了一声:大家没有投币刷卡的,请投币刷卡。嘴里说是大家,但眼睛只盯着刷鞋匠。刷鞋匠有些不自在了,他扬起头对司机说:“我投了的。”
     “投了怎么没听见响呢?”
     “是纸币!”
     “哼,纸币,这些乡下人……”
       司机冷笑着摇摇头,开始发动车子,准备出发。
这时,出乎他预料的一幕出现了,那个看起来一巴掌打不出三个屁的小个子乡下男人突然跳起来说,乡下人怎么了?乡下人就该被你怀疑?乡下人给钱坐车还要看你的白眼?
       司机出乎预料的遭到反击,有点懵了,他把车熄了火,扯下手套,回过头来准备认真地和刷鞋匠吵一架。他说,乡下人怎么了?乡下人了不起?乡下人 坐车可以不给钱?看你们那伙子人,上七八个人,投一两个硬币,还有五毛甚至一毛的。我还冤枉你们不成?
       刷鞋匠说,别人买不买票我不知道,我投了币买了票,你就不能冤枉我!
       车上赶着上班的人们开始鼓噪,司机觉得吵下去没意思,就转身准备继续开车,嘴里却有些不甘地说,你投没投,只有天知道了!
       说罢,戴上手套,吹起口哨,准备开车。他的表情激怒了刷鞋匠,刷鞋匠蹭地钻到驾驶台前,一把抢下车钥匙,大叫着,天知道,今天就要让天知道,把钱箱打开,验钱!
       司机仿佛是遭到小鸡突然袭击的老鹰,一下子没回过神来。待他反应过来之后,马上恢复了鹰的本色,从工具箱中取出一把铁扳手说,钥匙拿来!要不,老子把你当抢劫犯给收拾了。
       刷鞋匠两眼血红地瞪着他说,你今天就是打死我,也要把这事搞清楚!
       很快,接到报警的110来了,警察对刷鞋匠说:就算你买了票的,别闹了,行不?
        刷鞋匠梗着脖子说:不行!得开箱!
        司机扳手握得紧紧的,但当着警察的面又不敢有所作为。急着上班的人都坐别的车去了,只剩下几个不太急的人在车上看热闹。我也在车上,我要看看这件事的最后结果。警察没办法,就对司机说,你就把钱箱打开吧!遇上这犟人了,你还真没办法。
       司机说,钱箱贴了封条的,只有公司的财务人员能打开。
       警察给公司打了电话,半小时过后,公司一个经理和财务人员赶来了。经理说,这不是瞎胡闹吗?这么一箱钱,你就能认出你那一块?刷鞋匠从口袋里扯出一个牛皮纸做的钱包,里面整整齐齐地排着几张一元面额的钞票。他说,你查,里面保准有一张钱像这些钱一样,左上角有一小块黑胶布。
       经理从钱箱里果然找出了一张左上角贴着一小块黑胶布的钱,说,对,是有这么一块。好了,我宣布你是投了币的。
       刷鞋匠梗着的脖子一下子软了,他得意地冲司机一扬头说:“听着,是……投……了……的!”声音中竟带有几分哽咽。
车继续开。我蹭到刷鞋匠旁边坐下,问他,你咋想出这招的。刷鞋匠说,如果你遭怀疑挨白眼的次数和我一样多的话,你也会想出来的。
       你这可是毁损人民币啊!是违法行为!
       不碍事,能抠掉,一抠就掉!
        刷鞋匠一面说着,一面很认真地抠下一块,给我做示范。                          

同类题4

阅读理解

    Deborah Cohen is a senior natural scientist at the Rand Corp and the author of the book A Big Fat Crisis: The Hidden Forces Behind the Obesity Epidemic and How We Can End It. According to the book, there are lots of misunderstandings of obesity.

1).If you're obese, blame your genes.

    Obesity rates have increased. Yet, between 1980 and 2000, the number of Americans who are obese has doubled—too quickly for genetic factors to be responsible.

    At restaurants, a dollar puts more calories on our plates than ever before, because restaurant meals usually have more calories than what we prepare at home, so people who eat out more frequently have higher rates of obesity than those who eat out less.

2).If you're obese, you lack self-control.

    Research shows that if we are faced with too much information, we have a tendency to make poor dietary choices. Our world has become so rich in temptation that we can be led to consume too much in ways we can't understand. Even the most vigilant (警觉的) people may not be up to the task of controlling themselves.

3).Lack of access to fresh fruits and vegetables is responsible for obesity.

    Although the US Department of Agriculture estimates that fewer than 5 percent of Americans live in the “food deserts”, about 65 percent of the nation's population is overweight or obese. For most of us, obesity is not related to access to more fresh fruits and vegetables, but to the choices we make in supermarkets.

4).The problem is not that we eat too much, but that we don't exercise.

    Michelle Obama's “Let's Move” campaign is based on the idea that if kids exercise more, childhood obesity rates will decrease. But there was no significant decrease in physical activity levels as obesity rates climbed in the 1980s and 1990s. In fact, although a drop in work-related physical activity may account for up to 100 fewer calories burned, leisure physical activity appears to have increased. The problem is that we eat too much.