问题 选择题

下列有关物质提纯的叙述中不正确的是[ ]

A.乙酸乙酯中混有乙酸,可先用饱和Na2CO3溶液洗涤,然后将两层液体分开

B.可向鸡蛋清溶液中加入浓(NH4)2SO4溶液,然后得到沉淀滤出,即得较纯的蛋白质

C.可将油脂加入NaOH浓溶液中加热,然后过滤,滤出的溶液即为较纯的油脂

D.甘蔗是制备蔗糖的主要原料,榨出的甘蔗汁因含有色素而呈黄色,在制取蔗糖前应先加入适量的活性炭, 经搅拌、过滤、蒸发结晶,即得较纯的蔗糖

答案

答案:C

阅读理解

.

A maths talent who won fame this week for giving up a million-dollar prize is living with his mother in a simple flat in St Petersburg, co-existing on her ~30-a-month pension, because he has been

unemployed for many years.

The Sunday Telegraph tracked down the strange recluse (隐士 ) who shocked the maths world when  he solved a century-old puzzle known as the Poincare Conjecture.

Grigory Perelman's trouble comes from a split with a leading Russian mathematical institute, the

Steklov, in 2003. When the Institute in St Petersburg failed to re-elect him as a member, Dr Perelman

was left feeling an "absolutely ungified and untalented person", said a friend. He becEune unconfident and cut himself off.

Other friends say he cannot afford to travel to the International Mathematical Union's congress inMadrid, where many people want him to receive the maths equivalent(等价物) of the Nobel Prize, and that he is too modest to ask anyone to pay for his trip.

Interviewed in St Petersburg, Dr Perelman insisted that he was unworthy of all the attention, and

was uninterested in the prize.“I do not think anything that I say can be ofthe slightest public interest"

he said. "I am not saying that because I value my privacy, or that I am doing anything I want to hide.

There are no top-secret projects going on here. Ijust believe the public has no interest in me."

He continued: "I know that self-promotion happens a lot and if people want to do that, good luck

to them, bjt I do not regard it as a positive thing. I realised this a long time ago and nobody is going to

change my mind. Newspapers sliould be more discerning(有洞察力的) over who they write about.

They should have more taste. As far as I am concerned, I can't offer anything for their readers."

Dr Perelman has some small savings from his time as a lecturer, but is apparently unwilling to increase them with the $1 million offered by the Clay Mathematics Institute in Cambridge,Massachusetts, for solving one ofthe world's seven "Millennium Problems".

66. Grigory Perelman lives with his mother because

A. he has to look after her

B. his mother has a million dollars

C. he has been out of work for a long time

D. he is badly paid at the mathematical institute

67. The phrase "absolutely ungified and untalented person" shows that Dr Perelman felt

A. angry      B. discouraged    C. proud        D. confident

68. Grigory Perelman refused to accept the prize because .

A. he thought the prize was worthless

B. he didn't believe the news

C. he couldn't afford to travel to Madrid

D. he showed no interest in it

69. From the passage, we can infer that Grigory Perelman

A. solved the most difficult maths problem

B. has a strong personality

C. wanted to make himself known to all

D. didn't get on well with the press

70. What's the best title for the passage?

A. Great Mathematician Leads Simple Life

B. Maths Genius Abandons a Million-dollar Prize

C. Mathematics Institute Offers Grigory $1 Million

D. One ofthe World's Seven "Millennium Probtems" Solved

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