艾弗里和同事用R型和S型肺炎双球菌进行实验,结果如下表。从表可知() A.①不能证明

题型:单项选择题

问题:

艾弗里和同事用R型和S型肺炎双球菌进行实验,结果如下表。从表可知()

A.①不能证明S型菌的蛋白质不是转化因子

B.②说明S型菌的荚膜多糖有酶活性

C.③和④说明S型菌的DNA是转化因子

D.①~④说明DNA是主要的遗传物质

考点:高中生物人类对遗传物质的探索过程人类对遗传物质的探索过程题库
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At a certain time in our lives we consider every place as the possible sites(地点) for a house. I have thus searched the country within a dozen miles of where I live. In imagination I have bought all the farms, one after another, and I knew their prices.

The nearest thing that I came to actual ownership was when I bought the Hollowell place. But before the owner completed the sale with me, his wife changed her mind and wished to keep it, and he offered me additional dollars to return the farm to him. However, I let him keep the additional dollars and sold him the farm for just what I gave for it.

The real attractiong of the Hollowell farm to me were its position, being about two miles from the village, half a mile from the nearest neighbor, bounded(相邻) on one side by the river, and separated from the highway by a wide field. The poor condition fo the house and fences showed that it hadn’t been used for some time. I remembered from my earliest trip up the river that the house used to be hidden behind a forest area, and I was in a hurry to buy it before the owner finished getting out some rocks, cutting down the apples trees, and clearing away some young trees which had grown up in the fields. I wanted to buy it before he made any more of his improvements. But it turned out as I have said.

I was not really troubled by the loss. I had always had a garden, but I don’t thing I was ready for a large farm. I believe that as long as possible it is better to live free and uncommitted (无牵挂的). It makes but little difference whether you own a farm or not.

小题1:What do we know about the author?

A.He wanted to buy the oldest farm near where he lived.

B.He made a study of many farms before buying.

C.He made money by buying and selling farms.

D.He had the money to buy the best farm in the country.小题2:Why did the author decide to buy the Hollowell place?

A.It was of good market value.

B.It was next to the highway.

C.It was in a good position.

D.It was behind a nice garden.小题3:Why did the author want to buy the farm in a hurry?

A.He was afraid the owner might changes his mind.

B.He hoped to enlarge the forest on the farm.

C.He wanted to keep the farm as it was.

D.He was eager to become a farm owner.小题4:The underlined words “the loss” in the last paragraph refer to ___.

A.the money the author lost in buying the farm

B.the sale of the garden in the Hollowell place

C.the removal of the trees around the house

D.the failure to possess the Hollowell place小题5:What does the author believe as important in life?

A.To own a farm

B.To satisfy his needs

C.To be free from worries

D.To live in the countryside

题型:单项选择题

下列哪项措施无助于改善糖尿病患者的微量清蛋白尿症()。

A.血糖正常化

B.降低血压

C.降低肾脏丝球体内血压

D.补偿性增加清蛋白摄取量

E.使用血管紧张素转换酶(angiotensin-convertingenzyme,ACE.抑制药

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正常情况下,机体在空间的平衡由哪些感觉器官协调完成()。

A.视觉

B.本体感觉

C.大脑皮质

D.前庭迷路感觉

E.小脑锥体束

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简述教育学在中国的成长历程。

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脱盐水系统异常停止,只对切粒机系统造成影响。()

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