城市固体废物的生物学特质：（）。

阅读理解

       Dogs are friends of man. They work for us. They hunt (狩猎) with us. They play with us. But once,

all over the world, dogs are wild (野生的).

       Dogs go back to the Stoen Age. All dogs had the same ancestor(祖先). It is believed that this

ancestor was much like a wolf (狼). Other animals like the fox, came from this ancestor, too.

       Thousands of years ago, man began to tame (驯服)the wild dogs . When the dogs were tame, they

were trained (训练). The strong dogs became working animals . They were trained to pull heavy loads

(担子). They learned to keep watch over the sheep and other animals. Working dogs had other jobs, too.

       Some dogs were not strong. But they could help man hunt for game. Other dogs were best as pets.

       At first , there were only a few kinds of dogs. Today there are more than 100 kinds.

( )1. The word in the story that means an animal far bac k in another animal's family is

ancestor.                                                                                              

( )2. The story make us believe that Man has helped change animals.       

( )3. The strong dogs turned into foxes.            

( )4. Dogs are pets from the beginning.                

( )5. Dogs and man have been friends for a long time.             

等差数列{a_n}中，a₄=10且a₃，a₆，a₁₀成等比数列，求数列{a_n}前20项的和S₂₀．

如治疗半年无效，下列不能采用的治疗是

A．脾切除

B．长春新碱1～2mg/次，每周1次，连用4～6周

C．大剂量丙种球蛋白0.4g/kg，连用5天

D．血浆置换

E．骨髓移植

我国A公司与外国B公司于2003年1月10日签订了购买20万吨小麦的CIF合同。A公司开出信用证规定，装船期限为 2003年2月15～20日，由于B公司租用的甲船开往指定海湾地区港口时由于战争封锁而迟至2月21日才到达装货港，货物于2月22日装好后启运。因而，承运人签发了装船时间与信用证规定不一致的提单。 B公司为这批小麦投保了水渍险。2003年2月28日，甲船在途中遭遇海啸，小麦部分被浸。由于船舶迟延到达，致使目的地小麦价格下降，A公司为尽快处理小麦而大幅降价，承受了巨额损失。请分析案例，并回答下列问题：

关于案例中的提单说法正确的是： ( )。

A．提单是证明海上运输合同和货物由承运人接管或装船，以及承运人据以保证交付货物的凭证

B．提单是货物收据，可以证实承运人已按提单的记载收到托运人的货物

C．提单是债权凭证，提单的持有人可以对货物提出请求

D．提单是运输契约的证明，是处理承运人与托运人之间争议的法律依据

自动主汽门，调速汽门关闭时有卡涩，机组禁止启动。（）