题干

已知aXm+bYn两种离子的电子层结构相同,则a等于(   )

A:b+m+n

B:b+m﹣n

C:b﹣m+n

D:b﹣m﹣n

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A

同类题1

阅读下文,回答问题

    下午第一节课,同学们正在上自习。忽然,一只美丽的小鸟飞了进来。

    它落在了讲台上。小鸟的身子小巧玲珑___两只眼睛圆溜溜的像两颗黑宝石___羽毛是金黄色的___光滑油亮___在太阳的照射下闪烁着点点亮光___它不时还呜叫几声___声音是那样悦耳动听___

    “快抓住它!”不知是谁喊了一声。我们班的调皮鬼蒋培军就开始了捕(pǔ  bǔ)鸟行动。只见他猫着腰,蹑手蹑脚地靠近小鸟,忽然,向前猛地一捂,却扑了空。小鸟被他吓(xià  hē)得满教室乱飞。“快把窗户关上!”蒋培军提醒了一句。“嘭!嘭!”几声,教室立刻被封得严严实实。

    同学们有的拿本子在桌子上挥舞,有的索性拿起扫帚打它……同学们追它、围它、堵它,把小鸟折腾得筋疲力尽。蒋培军趁它不注意的时候一把抓住了它。

    只见它光滑的羽毛变得乱七八糟,眼睛惊恐地望着大家,似(shì  sì)乎在说:“放了我吧!”我不忍心再看到它那可怜的样子,说:“放了它……”.不等我说完,蒋培军连忙打断我的话:“这可是我好不容易抓到的,能轻(qīn  qīng)易放走吗?”我说:“鸟儿是人类的朋友,我们要好好地保护它们,怎么能伤害它们呢?”大家一致同意我的意见。此刻,蒋培军的脸微微红了,他若有所思地点了点头。只见他打开窗户,松开手说:“飞吧,小鸟!”小鸟振了振翅膀,向着蔚蓝的天空飞去了。

    看着它远去的身影,我仿佛看到它再一次回到森林中,和它的伙伴们一起歌唱。

同类题4

配对阅读。左栏是不同人的生活需求,右栏是七个不同的旅游景点。请为不同的人选择相应的景点。

(B)

____Liang and Wang, both teachers, are going to take their summer holidays at some beautiful seaside.They like good wine and shopping.

____Chen Hui and Li Hong, university students, want to travel with very little money, and would like to get to know the country by working with the local (当地的) people for two weeks.

____Mr.Zhang, a young and busy manager, needs a holiday to relax.He would like to go somewhere warm and sunny, where he can swim in the sea, and he enjoys sports and dancing.

____Mr.Lee and his wife, who have recently retired  (退休), want to see places of cultural and historic interest, but Mrs.Lee hates flying.

____Ling Xia,a nurse in a hospital in Guangzhou, hopes to spend her 21st birthday in the north and skate on real ice.

A.Seven Days on Jinsha Island

Seven­day holidays on Jinsha Island, lovely beach with golden sand and deep blue sea.Sailing and some other water sports as well as dancing to local music.

B.East China in Comfort

Comfortable coach tours around five cities in East China.Six days out of normal holiday season, seeing local culture.

C.A Four­day Holiday in Guilin

Relax yourselves for a four­day holiday in Guilin.Stay in the Lijiang Hotel.Taste delicious Guilin rice noodles.A tour on the Lijiang River by boat.

D.Holiday Homes in Sanya

Holiday flats in Sanya in summer season by the sea, yet near shops and restaurants.

E.One Day Travel in Guangzhou

Climb Mt. Baiyun in the morning, visit Yuexiu Park and other sceneries after lunch.A night time boat trip on Pearl River at 8:00.

F.One Week on Sun Island,Harbin

One­week holidays in the Full Moon Hotel.Beautiful flats with sights of Sun Lake. Skating, skiing and other winter sports.

G.Farm Holidays in Guizhou

Working holidays on a farm in Guizhou for one to three months, if prepared to work with the farmers.Rooms, food and trips all provided free—you only pay for the low cost traffic.