下列哪一个细胞里的染色体不成对存在（    ）

阅读下文，回答问题。

用你爱我的方式去爱你

       你突然打电话说要来我家，电话里，你轻描淡写地说：“听你二伯说，巩义有家医院治腿疼，我想去看看。先到你那里，再坐车去。你不用管，我自己去……”

       第二天，我还没起床你就来了。打开门后我看见你蹲在门口，一只手在膝盖上不停地揉着。你眉头紧锁，脸上聚满了密集的汗珠。我埋怨你不应疼成这样才去看医生，你却说没啥大事。

       去医院的途中，你走得那么慢，弓着身子，一只手扶着膝盖，一步一步往前移。我紧追过去，在你前面弯下腰，我说：“爸，我背你到外面打车。”你半天都没动，我扭过头催你，才发现你正用衣袖擦眼，你的眼睛潮红湿润，有点儿不好意思地说：“风迷了眼。”又说：“背啥背?我自己能走。”纠缠了半天，你拗不过我，终于乖乖地趴在我背上，像个听话的孩子。我攒了满身的劲背起你，却没有想象中那样沉。那一瞬，我有些怀疑：这个人，真的是我曾经健壮威武的父亲吗?你双手搂着我的脖子，在我的背上不安地扭动着，身子使劲弓起来，紧张得大气都不敢出。

       到小区门口，不过二十几米的距离。你数次要求下来，都被我拒绝。爸爸，难道你忘了，你曾经也这样背着我，走过多少路啊?

       那一年我在工地被钢板伤，右腿险些被砸断，腰椎也被挫伤。在漫长而繁杂的治疗过程，你背着我，去五楼做脊椎穿刺，去三楼做电疗，上上下下好几趟。那年，你50岁，日夜的焦虑使你身心憔悴;我18岁，在营养和药物的刺激下迅速肥胖起来。50岁的你背着18岁的我，一趟下来累得气都喘不过来。在你的精心照料下，8个月后，我开始扔下拐杖能自己走了。

       这次去在医院做检查，你不停地问我：“到底怎么样?不会很严重吧?”我紧紧握着你的手，你厚实粗糙的大手在我的掌心里不停地颤抖。我第一次发现，你其实是那么害怕。是骨质增生，必须手术治疗。医生说，真想象不出，你如何能忍得了那样的疼?

       那天护士为你输液，那个实习的护士，一连几针都没有扎进血管。我一把推开她，迅速用热毛巾敷在你的手上。一向脾气温和的我，第一次对护士发了火：“你能不能等手艺学好了再来扎?那是肉，不是木头!”护士尴尬地退了下去， 你看着暴怒的我，眼睛里竟然有泪光闪烁。我猛然记起，几年前，你也曾这样粗暴地训斥过为我扎针的护士。

       手术很成功。你被推出来时，仍然昏睡着。我仔细端详着你，你的脸沟壑纵横，头发白了大半，几根长寿眉耷拉下来……我想起你年轻时拍的那些英俊潇洒的照片，忽然止不住地心酸。

       几个小时后，你醒了，看见我在，又闭上眼睛。一会儿，又睁眼，虚弱地叫，“尿……尿……”我赶紧拿出小便器，放进你被窝里。你咬着牙，很用力的样子，但半天仍尿不出来。你挣 扎着要站起来，牵动起伤口的疼痛，巨大的汗珠从你的额角渗出来。我急了，从背后抱起你的身体，双手扶着你的腿，把你抱了起来。你轻微地挣扎了几下后，终于像个婴儿一样安静地靠在我的怀里，那么轻，那么依恋。

       出院后你就住在我家里。每天，我帮你洗澡按摩，照着菜谱做你喜欢吃的菜，绕很远的路去为你买羊肉汤。阳光好的时候，我带你去小公园听二胡，每天早上催你起床锻练，你在前面慢慢走，我在后面紧紧跟随……所有的人都羡慕你有一个孝顺的儿子，而我知道，这些，都是你传承给我的爱的方式。只是我的爱永远比不上你的爱，宽阔辽远一如无际的大海，纯粹透明没有丝毫杂质，而我，只能用杯水，去回报大海。

选出下列词语字形完全正确的一组（    ）

    Could the device, smartphone or PC，which you're using affect the moral decisions you make when using it? To test it, researchers presented multiple dilemmas to a sample set of 1,010 people. The participants were assigned a device at random.

    One case of the questions participants were asked is the classic “trolley (有轨电车) problem”: A runaway trolley is headed towards five people tied up on a set of train tracks. You can do nothing, resulting in the deaths of five people, or push a man off a bridge, which will stop the trolley. The practical response is to kill one man to save five lives, which 33.5 percent of smartphone users chose, compared to 22.3 percent of PC users.

    “What we found in our study is that when people used a smartphone to view classic moral problems, they were more likely to make more unemotional, reasonable decisions when presented with a highly emotional dilemma, ”Dr Albert Barque-Duran, the lead author of the study, told City, University of London. “This could be due to the increased time pressure often present with smartphones and also the increased psychological distance which can occur when we use such devices compared to PCs.”

    As for why the researchers started this study, Dr Barque-Duran noted, “Due to the fact that our social lives, work and even shopping take place online, it is important to think about how the contexts where we typically face moral decisions and are asked to engage in moral behavior have changed, and the impact this could have on the hundreds of millions of people who use such devices daily.” It's clear that we need more research on how our devices affect our moral decision making because we're using screens at an ever-increasing rate.

读等高线地形图，L为河流。回答下列各题。