题干

关于DNA分子的叙述错误的是 

A:绝大多数生物体的遗传信息都存在于DNA分子中

B:DNA分子中,每个脱氧核糖分子只与1分子含氮碱基和1分子磷酸基团相连

C:DNA分子中碱基对排列顺序的千变万化构成了DNA分子的多样性

D:DNA分子中碱基对特定的排列顺序构成了每个DNA分子的特异性

上一题 下一题 0.0难度 选择题 更新时间:2018-11-07 05:17:17

答案(点此获取答案解析)

B

同类题4

阅读下面短文,从每题所给的A、B、C和D四个选项中,选出最佳选项。

A

Safety and Security Procedures

   Your safety and the security of your personal property(财产) are of the primary concern to those of us who welcome you as our guest. We urge you to take advantage of the following suggestions.

 YOUR VEHICLE

   Lock your vehicle and do not leave money or valuable items inside. We are not responsible for their loss.

TRAVELING

   Be good at noticing things around you when sightseeing or traveling. Stay in heavily traveled areas. Don't display large amounts of cash.

GUEST ROOM SECURITY

   For additional security, use the deadbolt (插锁) provided on your door and make sure the windows are locked. As an additional precautious measure, please secure the secondary locks provided. Do not admit anyone to your room without first making identification. A one-way viewer is provided in your door to assist with identification. If there is any doubt about the person's identity, please contact the Front Desk.

SAFETY BOXES

   Do not leave money or valuables in your room or vehicle. We provide free safety boxes for you. We are not responsible for items left in room valued over $200.

KEYS

   Safeguard your key. Please do not leave it in the door. Do not give your key to others or leave it unattended. Please leave your key at the Front Desk when you check out.

FIRE

   Please familiarize yourself with the nearest fire exits. Report fire or smoke to the hotel operator. In the unlikely event of a fire, please move quickly and calmly to the nearest safe exit and leave the building. Avoid the use of the elevator.

REPORTING

   Please report any suspicious activity, or safety concerns to management.

同类题5

                                                                                                想起那年读书时    谷煜
    ①那年我十岁,三年级,天不怕地不怕的年龄,不管生疏,常常和同学去串门。到了别人家里,我常常安静地直盯着土屋墙壁上的黑白报纸。那些报纸,是一些富裕人家不知从哪里弄来的,贴在墙上,给土屋一点美观,不至于到处露着暗灰的墙皮。 
    ②有字可读真好。看着看着,我的身子会趴下,因为靠底下的一些字实在是看不清了。而下面的报纸,往往更旧一些,泛着黄色,伴随着一丝丝潮潮的味道。而于我,是温润,是隆重,闪着华丽的光,仿佛是琥珀。 
    ③慢慢读完一面墙,真畅快呀。当时除了课本之外,再也找不到书可读,偶然在同学家发现这样的“报纸墙”,自是欣喜若狂,也就有了这“串门”的雅好。 
    ④慢慢地,很多人知道我喜欢“读字”,便有人告诉我,谁谁那里有小人书,可以借着看看。听了那些陌生的名字,怵头,我哪里认识人家呀?怎么办?只好央求妈妈去借,大人总会和人家说上话的吧。 
    ⑤那时候的小人书,人人当宝贝,自是不会轻易借出。妈妈便苦口婆心地求人家,一遍遍保证,不会弄丢的,不会弄脏的,不会弄扯的,一定按时还……终于,在人家一遍遍的叮嘱里,在犹豫的眼光里,我拿到了小人书。 
    ⑥我抱着书,飞奔回家,小心翼翼放在床头一角,赶紧吃饭写作业,然后扎在灯下,一声不吭,一页页仔仔细细看过去。夜深了,我抚摸着小人书,恋恋不舍地睡去,天亮,它就该物归原主了。 
    ⑦还有让人欢喜的是过年放鞭炮,因为那时很多鞭炮是用废弃的书本卷成的。鞭炮在炸开的刹那,产生很多带着字的碎片,它们仿佛一个个精灵,舞蹈着,纷纷朝我而来。我笑着跑着去迎接那些碎片,在碎片里,看到一个个的“断句”,或者几个词语,那种此起彼伏的文字阅读,仿佛海边的波浪,一波波的涌动而来,真好。 
    ⑧当然,也会有大的收获。包鞭炮的纸张总是大一些,我总是悄悄去捡来,展开,抚平,偶尔会读到一段故事,也许没有开头,也许没有结尾,但有一些词:万水千山,碧波荡漾,寂静芬芳,花来衫里,影落池中……它们总像是春天拂过的风,暖暖的,通身清透。 
    ⑨后来,我拥有了淋漓畅快的读书机会,全因为村里一户人家,做起了废品收购的买卖。他家的院子里,堆满了瓶瓶罐罐,纸箱书本。没有任何人邀请,我就成了人家的“座上客”,只要一有空闲,就跑到人家的院子里,那个小小的院落,被我的双脚一寸寸地丈量过。也是在那个时候,我看到了一本本完整的杂志,一本本很旧很破,几乎还是繁体字的《西游记》《后唐演义》……一路读起来,磕磕绊绊的,但总算能读过去。我坐在小小的院子里,一个有书的天地,令人满心欢喜。 
    ⑩慢慢地,条件好了,我去到乡里读书,可读的书多了起来。但是,却因为爱熬夜,受到了妈妈的限制。为了防止妈妈批评我,我钻在被窝里打着手电筒看,电池没得太快,也不是长久之策,就和妈妈打起游击战。 
    ⑪那时候没有雾霾,夜晚总是清亮亮的,我就盼着每个月的十五六,能在月光下看,但看得眼睛疼啊,试了几次之后,也就放弃了。⑵月光下,窗台边,一股清凉,几声蟋蟀鸣,是在我年少的记忆里最美好的场景。 
    ⑫后来啊,读书的种类,读书的场地慢慢丰富起来。不变的是,读书的每一个刹那,都仿佛是时光滋养的花枝,慢慢开出耀眼的花。多年以后,到底还是因为这书,生出了一些灵性,鲜亮了人生。蓦然回首,一路走来的读书时光,在阳光丽日里,散发着温暖、生动、可爱、亲切。一纸一片,在呼啦啦的青春里,依然于素色中呈现着夺目的光芒。素手拈花,好似故人来。这好玩的读书往事,想想就笑意盎然,关乎经脉,关乎底气,怎不值得终生记忆?