准驾车型为小型自动挡汽车的，可以驾驶低速载货汽车。

机械设备试运转前应具备( )条件。

A．设备及其附属装置、管路等均应全部施工完毕，施工记录及资料应齐全

B．需要的能源、介质、材料、工机具、检测仪器、安全防护设施及用具等，均应符合试运转的要求

C．对大型、复杂和精密设备，应编制试运转方案或试运转操作规程

D．参加试运转的人员，应熟悉设备的构造、性能、设备技术文件，并应掌握操作规程及试运转操作

E．设备及周围环境应清扫干净，设备附近不得进行有粉尘的噪声的作业

真空中两个相同的金属小球A和B，带电量分别为Q_A=2×10^-8C和Q_B= －4×10^-8C，相互作用力大小为F.若将两球接触后再放回原处，则它们之间的作用力大小将变为

A．8F

B．F

C．

D．

镰刀形细胞贫血症是一种单基因遗传病，是由正常的血红蛋白基因(HbA)突变为镰刀形细胞贫血症基因(HbS)引起的。在非洲地区黑人中有4％的人是该病患者，会在成年之前死亡，有32％的人是携带者，不发病但血液中有部分红细胞是镰刀形。下图是该地区的一个镰刀形细胞贫血症家族的系谱图。回答以下相关问题：

(1)非洲地区黑人中HbS基因的基因频率是__________。科学家经调查发现，该地区流行性疟疾的发病率很高，而镰刀形红细胞能防止疟原虫寄生，那么该地区基因型为______的个体存活率最高。该地区黑人迁移到不流行疟疾的美洲地区后，HbS基因的基因频率将逐渐_________。

(2)据系谱图可知，HbS基因位于_____染色体上。Ⅱ₆的基因型是________，已知Ⅱ7也来自非洲同地区，那么Ⅱ₆和Ⅱ₇再生一个孩子，患镰刀形细胞贫血症的概率是______。

(3)Ⅱ₆和Ⅱ₇想再生一个孩子，若孩子已出生，则可以在光学显微镜下观察其______形态，从而诊断其是否患病。若孩子尚未出生，则可以从羊水中收集少量胎儿的细胞，提取出DNA，用___________为原料在试管中复制出大量DNA，然后进行基因诊断。

(4)如下图所示，该基因突变是由于_____碱基对变成了_____碱基对，这种变化会导致血红蛋白中______个氨基酸的变化。

HbA基因突变为HbS基因后，恰好丢失了一个MstⅡ限制酶切割位点。用MstⅡ限制酶切割胎儿DNA，然后用凝胶电泳分离酶切片段，片段越大，在凝胶上离加样孔越近。加热使酶切片段解旋后，用荧光标记的CTGACTCCT序列与其杂交，荧光出现的位置可能有下图所示的三种结果。若出现______结果，则说明胎儿患病；若出现_____结果，则说明胎儿是携带者。

2÷9的商用循环小数表示是______，精确到十分位是______．

阅读下面短文，按照要求回答问题。

                                                      The Monster of Lake Tianchi

     The "Monster of Lake Tianchi" in the Changbai Mountains in Jilin province, northeast China, is back in

the news after several recent sightings. The director of a local tourist office, Meng Fanying, said the monster,

which seemed to be black in colour, was ten metres from the edge of the lake during the most recent sighting.

"It jumped out of the water like a seal-about 200 people on Changbai's western peak saw it," he said. Although

no one really got a clear look at the mysterious creature, Xue Junlin, a local photographer, claimed that its head

looked like a horse. 

     In another recent sighting, a group of soldiers claim they saw an animal moving on the surface of the water.

The soldiers, who were walking along the side of the lake, watched the creature swimming for about two

minutes. "It was greenish-black and had a round head with 10-centimetre horns", one of the soldiers said.

     A third report came from Li Xiaohe, who was visiting the lake with his family. He claims to have seen a

round black creature moving quickly through the water. After three or four hundred metres it dived into the

water. Ten minutes later the monster appeared again and repeated the action. Mr Li Xiaohe said that he and his

family were able to see the monster clearly because the weather was fine and the lake was calm.

     There have been reports of monsters in Lake Tianchi since the beginning of the last century, although no

one has seen one close up. Some photos have been taken but they are not clear because it was too far away.

Many people think the monster may be a distant cousin of the Loch Ness monster in Scotland. They also think

that there might be similar creatures in other lakes around the world. Scientists, however, are sceptical. They

say that the low-temperature lake is unlikely to be able to support such large living creatures.

     Lake Tianchi is the highest volcanic lake in the world. It is 2,189 metres high and covers an area of about

ten square kilometres. In places it is more than 370 metres deep.

1. How many sightings of the monster does the article report?

    _________________________________________________________________________________

2. Who saw the monster clearly, and why?

    _________________________________________________________________________________

3. Which description of the monster is most detailed?

    _________________________________________________________________________________

4. When was the monster first sighted?

    _________________________________________________________________________________

5. What is special about Lake Tianchi?

    _________________________________________________________________________________