气球被水平吹来的风吹为如左下图所示的情形，若测得绳子与水平面的夹角为37°，水平

18×500，积的末尾有两个0．…______．

阅读下列材料：

材料一“义和团，起山东，不到三月遍地红。孩童个个拿起刀，保国逞英雄。”  ——民谣

材料二“男练义和团，女练红灯照。砍掉电线杆，扒了火车道，杀尽东洋兵，再和大清闹。” ——民谣

材料三“我是一个反对帝国主义者，不赞成兀鹰把爪子伸到任何国家去……，义和团是爱国者。他们爱他们自己的国家胜过爱别的民族的国家……义和团主要是想把我们赶出他们的国家。” ——马克·吐温《我也是义和团》

请回答：

（1）义和团“起山东”和“不到三月遍地红”的背景是什么？

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（2）读材料一、二，哪些文字能反映出义和团的深厚群众基础？

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（3）“砍掉电线杆，扒了火车道。”这些行为反映了义和团对外来事物的什么态度？

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（4）读材料三，结合当时情况，作者所说的“兀鹰”具体指谁？你对他的观点是怎么看的？义和团后来是怎样失败的？

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钢筋的运输保管工作极为重要，对钢筋的品种、牌号必须分清，不能混乱，应采用（）制。

上腔静脉阻塞时，腹壁静脉血流方向为

A．脐水平以上静脉血流向上，脐以下血流向下
B．脐以上水平静脉血流向下，脐以下血流向上
C．腹壁静脉血流全部向上
D．腹壁静脉血流全部向下
E．以脐为中心血流向四周

A patrol team of sea lions and dolphins featured in a large-scale military exercises being conducted by the U. S. and its allies in the Pacific Ocean. The machine (1) took part in simulated mine recovery and mine detection missions during the biennial Rim of the Pacific Exercise (RIMPAC) war games. The (2) started on June 19 and will run (3) Friday.
"There are a number of mechanical systems that work in those areas. (4) high-tech gadgets deployed by the military can’t (5) the natural skills of dolphins and lions," said Tom Lapuzza, spokesman for UN Navy’s Marine Mammal Program. Sea lions have "incredible good underwater (6) " and can dive down to 300 meters to catch a recovery line to a mine, he said. Dolphins use sonar to (7) mine.
Human beings have a long (8) of training animals to join the military. Horses have been the most widely-used animals (9) the recorded history of (10) . In early times, horses were used to (11) chariots or to (12) armored forces. With the development of modem weapons and motorized (13) , the use of horses for military purposes fell into (14) . (15) , horses were still used (16) by the German army during World War II for transporting (17) and equipment, including artillery.
During World War II, (18) with explosives strapped to their backs were used as anti-tank weapons. In other (19) , they were used for detecting mines. Some dogs were also used as messengers.
Other animals have also (20) in the military. Recorded history shows the use of elephants for military purposes as early as 1,100 B. C.. They were employed during World War II by both the Japanese army and the (21) .
There are records showing that over 100,000 reindeer were used by Finland to tow sleds during World War II. They carried the (22) to hospitals, brought supplies to the troops and moved heavy anti-tank weapons. It is well documented that oxen have been (23) used in war as improvised beasts of burden. During World War II, spiders were employed by the Allies to spin silk for (24) in cross-hairs on bomb scopes and other optical instruments. People also are finding that Vampire bats’ ability to use echolocation is very interesting as we (25) to learn how it works and it may benefit the army.