问题 选择题

下列图象关系合理的是(   )

A.在部分变质的NaOH溶液中加入稀硫酸

B.在饱和的KNO3溶液中加入KNO3晶体

C.向pH=9的KOH溶液中不断加水

D.分别将等质量的Fe和Mg加入两份质量相同浓度相同的稀盐酸中

答案

答案:A

题目分析:A、NaOH能与二氧化碳反应生成碳酸钠而变质;所以部分变质的氢氧化钠溶液中存在氢氧化钠和碳酸钠;当加入硫酸后,硫酸先与氢氧化钠反应,此时不生成气体。氢氧化钠反应完后再与碳酸钠反应,生成气体。图像符合此特点。此项正确。B. 因KNO3溶液已饱和,所以再加入KNO3晶体也不会再溶解,溶质质量分数不变。此项错误。C. KOH溶液呈碱性,加入水其溶液的碱性会逐渐减弱,但溶液仍呈碱性,不会变为中性或酸性。此项错误。D. 镁的活动性比铁强,图像不符合此特点。此项错误。

问答题 简答题
单项选择题

The United States is usually given credit for creating and developing the musical comedy as it is known today. The first musical shows were based (1) everyday American life and the (2) development of the form took place in the United States for more than half a century. (3) the early 1970s, (4) , the London theater has (5) the Broadway stage.

The Black Crook, which opened at Niblo’s Garden in New York City on Sept. 12, 1866, is usually (6) as the inspiration for musical comedy. A troupe of French ballet dancers (7) to be stranded in New York without work (8) a fire damaged the theater (9) they had been booked. In order to keep a (10) to them, the theater producer put the dancers into a melodrama written by Charles M. Barres.

The first stage production that was (11) a musical comedy was a show that was (12) from the Prince of Wales Theater to the Gaiety Theater in London in 1892. Staged by George Edwards, the show called In Town featured a chorus line of Gaiety Girls. The (13) year A Gaiety Girl was equally successful, and a (14) of the show played in New York in the same year. When it was (15) in newspapers, it was designated a musical comedy and regarded as a new (16) of entertainment.

It did not take the form long to (17) in the United States. Almost (18) one of the most renowned talents of the American stage went to work on his own musicals. The singer-dancer George M. Cohan staged Little Johnny Jones in 1904. Cohan, (19) own life story was made into the musical George M (1968), also wrote the books, words, and (20) for Forty-five Minutes from Broadway ( 1906 ), The Little Millionaire ( 1911 ), The Song and Dance Man ( 1923 ), and American Born (1925).

19()

A.when

B.which

C.that

D.whose