给水泵、给水管路及阀门正常，但在运行中提高给水泵的频率，增大给水泵的出口压力给汽包进

下列除去杂质的方法正确的是[ ]

A.用足量的稀硫酸除去铁粉中少量的铜粉

B.用适量的K₂CO₃溶液除去NaCl溶液中少量的CaCl₂

C.用足量的NaOH溶液除去CO气体中少量的CO₂

D.用适量的稀盐酸除去NaOH溶液中的少量的Na₂CO₃

第三部分：阅读理解（共20小题；每小题2分,满分40分）

阅读下列短文,从每篇短文后所给各题的四个选项（A、B、C和D）中,选出最佳选项,并在答题卡上将该项涂黑。

No one knows where the phrase "Indian summer" got started, we are sure that the phrase was wellknown by the year 1778,because Crevecoeur, an American writer, described it like this:"a hard frost(霜冻)follows the autumn rains. This prepares the ground to receive the snows of winter. But before the snows come, the earth turns warm once again and there are a few days of smoke and mildness called Indian summer."

There is a story about Indian summer that goes back to the very first settlers of the New World. The first frost meant winter was coming. Snow would soon follow.

The Indians, seeing the settlers preparing for winter, told them not to hurry. The weather would turn warm again, mild breezes would blow and the sky would turn soft and smoky. And so it did. The sun became hotter,and a bright warm smoke flowed over the fields and woods. The settlers, remembering the words of the Indians, called this wonderful period Indian summer.

But the Indians have their own stories about this late period of warm weather. One of their stories is about a god called Shawondasee.

Shawondasee was a sad god because he had lost the love of a tall and beautiful Indian maiden. The sad and beautiful story caught the imagination of the American poet Henry Wadsworth Longfellow. In 1855 he included the story of Shawondasee in his poem "The song of Hiawatha".

The story goes like this: God Shawondasee, fat and lazy, lived under the dreamy and never-ending southern sun. He sent birds and wild geese to the north, as well as melons and grapes. He smoked a big pipe, and as the smoke rises, it filled the sky with dreamy softness, gave a bright shine to the water and brought the tender Indian summer to the melancholy northland.

There is something about this period of warm weather that gives people a lift and makes them feel warm and happy before the long snows of winter come.

61.Which season does "Indian summer" refer to?

A. Early spring.       B. Late summer.         C. Mid-autumn.        D. Early winter.

62.Which of the following best describes the weather of this period of time?

A. Hot and humid.    B. Warm and mild.     C. Cool and bright.    D. Cold and smoky.

63.The Indians' explanation to this natural phenomenon is that God Shawondasee_______.

A. lived under the dreamy southern sun         B. took pity on the homeless settlers

C. smoked a lot because of his bad mood       D. lent his smoking pipe to the Indians

64.What is the meaning of the underlined word "melancholy"?

A. Sad and lonely.                  B. Dreamy and exciting.

C. Soft and musical.                D. Warm and happy.

与图书相比，期刊的媒体特征除了回笼资金较快外还有（）

A.开本较大，页数较少

B.出版周期严格固定

C.可以无限期的延续出版

D.均通过邮局发行

E.一般不会再版或重印

干扰素的主要作用机制是

A．直接灭活病毒
B．阻碍病毒进入细胞
C．抑制病毒释放
D．诱导细胞产生抗病毒蛋白
E．阻碍病毒脱壳