用18.4mol•L-1的浓H2SO4配制100mL浓度为1mol•L-1的H2

题型:问答题

问题:

用18.4mol•L-1的浓H2SO4配制100mL浓度为1mol•L-1的H2SO4,其操作可分为以下各步:

(A)用量筒取______mL浓H2SO4缓缓注入装有约50mL蒸馏水的烧杯中,并用玻璃棒不断搅拌

(B)用约30mL蒸馏水,分成三次洗涤烧杯和玻璃棒,将每次洗液都倒入100mL容量瓶里

(C)将稀释后H2SO4小心倒入100mL容量瓶里

(D)检查100mL容量瓶口部是否会发生滴漏

(E)将蒸馏水直接加入容量瓶,至液面接近环形刻度线______处

(F)盖紧瓶塞,反复颠倒振荡,摇匀溶液

(G)用______向容量瓶里逐滴滴入蒸馏水,至液面最低点恰好和环形刻度线相切

(1)将上述各步的空白处补充完整.

(2)正确的操作顺序是(字母填写)______.

(3)进行A步操作应选择下列量器:①10mL量筒;②50mL量筒;500mL量筒;④1000mL量筒中的(填序号)______.

考点:配制一定物质的量浓度的溶液
题型:问答题

男孩,5岁,发热,喷射性呕吐3天,伴剧烈头痛1天,全身性抽搐2次,每次约3分钟缓解,抽后嗜睡。查体:神志恍惚,面色灰白,体温38.8℃,末梢血检查:白细胞明显升高,以中性粒细胞为主。

若患儿拟诊化脑,最可能见到的体征为()

A.呼吸不规则,深昏迷,对光反射消失

B.颈强,瞳孔不等大

C.颈强,神经系统检查有异常

D.跟膝、腱反射亢进

E.四肢瘫软,肌张力低下

题型:问答题

They like using the Internet.They have lots of pocket money to spend.And they spend a higher proportion of it online than the rest of us.Teenagers are just the sort of people an online seller is interested in, and the things they want to buy-games, CDs and clothing-are easily sold on the Web.

But paying online is a tricky business for consumers who are too young to own credit cards.Most have to use a parent’s card.They want a facility that allows them to spend money.

That may come sooner than they think: new ways to take pocket money into cyber (网络的) space are coming out rapidly on both sides of the Atlantic.If successful, these products can stimulate online sales.

In general, teenagers spend huge amounts: $153bn (billion) in the US last year and £20bn annually in the UK.Most teenagers have access to the Internet at home or at school-88 percent in the US, 69 percent in the UK.According to the Jupiter Research, one in eight of those with Internet access has bought something online-mainly CDs and books.

In most cases, parents pay for these purchases with credit cards, an arrangement that is often unsatisfactory for them and their children.Pressing parents to spend online is less productive than pressing on the high street.They are more likely to ask “Why?” if you ask to spend some money online.

One way to help teenagers change notes and coins into cybercast is through prepaid cards such as Internet Cash in the US and Smart cards in the UK.Similar to those for pay-as-you-go mobile telephones, they are sold in amounts such as£20 or $50 with a concealed 14-digit number that can be used to load the cash into an online account.

小题1:What does the word “They” in paragraph 1 refer to?

A.Sellers.

B.Buyers.

C.Teenagers.

D.Parents.小题2:According to the passage, which of the following statements is TRUE?

A.More than half of the teenagers in the US and the UK have Internet access.

B.Teenagers pay for goods online with their own credit cards.

C.Most teenagers in the US and the UK have bought something online.

D.Teenagers found it easier to persuade parents to buy online than in a shop.小题3:A new way to help teenagers shop online is to use ______.

A.a new machine

B.special coins and notes

C.prepaid cards

D.pay-as-you-go mobile phones小题4:What is the passage mainly about?

A.Online shopping traps.

B.Internet users in the US and the UK.

C.New credit cards for parents.

D.The arrival of cyber pocket money.

题型:问答题

由于市场的状况变化,生产计划作必要调整时,不必征询企业采购部门的意见。

题型:问答题

对于用户,什么最重要()。

A、操作

B、数据

C、权限

D、应用

题型:问答题

常规胸片,对哪种结构显示最差()

A.胸椎

B.肋骨

C.肋软骨

D.胸锁关节

E.肺门

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