问题 选择题

有五瓶失去标签的溶液,它们分别为:①Ba(NO3)2、②NaCl、③NaOH、④Fe2(SO4)3、⑤Na2SO4,如果不用其他试剂(包括试纸),用最简便的方法将它们一一鉴别开来,则鉴别出各物质的先后顺序中,合理的是(    )

A.④③①⑤②

B.④①③⑤②

C.①⑤③④②

D.③④①⑤②

答案

A.B 

题目分析:铁离子在溶液中显黄色,首先观察溶液的颜色,显黄色的是硫酸铁;然后将硫酸铁滴入剩余的四种溶液中,一种会出现红褐色沉淀,是氢氧化钠;另一种会出现白色沉淀,是硝酸钡;及然后将硝酸钡滴入剩余的两种溶液中,出现白色沉淀的是硫酸钠,没有现象的是氯化钠。因为①Ba(NO3)2及③NaOH与④Fe2(SO4)3产生沉淀的顺序可以颠倒;②NaCl、⑤Na2SO4与①Ba(NO3)2产生现象的顺序可以颠倒,故正确顺序可以是:④③①⑤②或④①③⑤②或④③①②⑤或④①③②⑤,故选A.B

选择题
单项选择题

Many foreigners who have not visited Britain call all the inhabitants English, for they are used to thinking of the British Isles as England. (1) , the British Isles contain a variety of peoples, and only the people of England call themselves English. The others (2) to themselves as Welsh, Scottish, or Irish, (3) the case may be; they are often slightly annoyed (4) being classified as "English".

Even in England there are many (5) in regional character and speech. The chief (6) is between southern England and northern England. South of a (7) going from Bristol to London, people speak the type of English usually learnt by foreign students, (8) there are local variations.

Further north regional speech is usually " (9) " than that of southern Britain. Northerners are (10) to claim that they work harder than Southerners, and are more (11) They are open-hearted and hospitable; foreigners often find that they make friends with them (12) Northerners generally have hearty (13) : the visitor to Lancashire or Yorkshire, for instance, may look forward to receiving generous (14) at meal times.

In accent and character the people of the Midlands (15) a gradual change from the southern to the northern type of Englishman.

In Scotland the sound (16) by the letter "R" is generally a p sound, and "R" is often pronounced in words in which it would be (17) in southern English. The Scots are said to be a serious, cautious, thrifty people, (18) inventive and somewhat mystical. All the Celtic peoples of Britain (the Welsh, the Irish, the Scots) are frequently (19) as being more "fiery" than the English. They are (20) a race that is quite distinct from the English. (289 words)

Notes: fiery 暴躁的,易怒的。

(15)()

A.designate

B.demonstrate

C.represent

D.reckon