一只杯子装满水后的总质量是m1=200g，放入小石块后，杯子、水、小石块的总质量

尽管阻碍重重，比特币依然在越来越接近人们的日常生活。监管层面的风险和飙升的价格，促使一些炒作家将目光放在了比特币的替代品上，全球涌现出了五六十种 “山寨”比特币的电子虚拟货币，如莱特币、质数币、名币等。对于比特币，下列说法正确的是（  ）

A．属于货币，因为它在虚拟世界中充当一般等价物

B．不属于货币，因为它是无形的，不是商品

C．属于特定的虚拟商品，因为它是劳动产品又用于交换

D．属于货币，因为它有价值，并能够衡量和购买网络增值服务

免疫组化技术的优点不包括

A．高特异性

B．高敏感性

C．形态学的直观性

D．精确定量分析

E．能对抗原表达情况进行分析

Scientists in Canada say big ocean fish have almost disappeared from the world since the start of industrial fishing in the nineteen-fifties. The scientists found that population of large fish like tuna; swordfish and cod have dropped by ninety percent in the past fifty years.

The study took ten years. The researchers gathered records from fishing businesses and governments around the world. The magazine Nature published the findings.

The scientists say the common method called longline fishing is especially damaging to populations of large fish. This method involves many fishing lines connected to one boat. These wires can be close to one-hundred kilometers long. They hold thousands of sharp metal hooks to catch fish.

Longline fishing is especially common in the Japanese fishing industry. Records showed that Japanese boats used to catch about ten fish for every one-hundred hooks. The study says longline fishing boats now might catch one fish per hundred hooks.

The scientists say industrial fishing can destroy groups of fish much faster than in the past. The study suggests that whole populations can disappear almost completely from new fishing areas within ten to fifteen years.

Ransom Myers of Dalhousie University in Nova Scotia led the study with Boris Worm of Dalhousie and the University of Kiel in Germany. Mister Worm says the destruction could lead to a complete re-organization of ocean life systems. Mister Meyers says the decreased number of large fish is not the only worry. He says even populations that are able to reproduce do not get the chance to live long enough to grow as big as their ancestors(祖先). He says not only are there fewer big fish, they are smaller than those of the past.

American government scientists say even with the best efforts to protect fish populations, decreases are to be expected.

小题1:Where is the passage probably taken from?

A．A story book.

B．A business magazine.

C．An environment report.

D．An economic survey.小题2:Big fish have gradually been disappearing especially because ________.

A．longline fishing method is used

B．sea water is getting polluted

C．mankind destroys the environment

D．governments don’t make the best efforts小题3:Which of the following shows the fact that the populations of large fish have dropped?

A．Today’s “large”fish are smaller than those of the past.

B．Longline boats now might catch fewer fish every one-hundred hooks.

C．Fish even able to reproduce don’t have the chance to live longer.

D．Japanese boats could catch about ten fish for every 100 hooks.小题4:What can be the best title?

A．Discoveries Canadian Scientists Have Made

B．Japanese Fishing Industry

C．Losses of Big Fish

D．Modern Fishing Methods小题5:When did the researchers begin to survey the decreasing of large fish?

A．In the 1960s.

B．In the 1970s.

C．In the 1980s.

D．In the 1990s.

议论文的“三要素”是( )

A．论点、论据、结论

B．引论、论据、结论

C．立论、驳论、正论

D．论点、论据、论证

COM40/3捻线车速8000转/分，捻度12.5捻，折80/2车速11000转/分、捻度22.76捻，折合系数为（）

A、0.352

B、0.3

C、0.252

D、0.2