自给式呼吸器一般应具有至少为()的持续工作时间的能力。A.10min B.15min

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问题:

自给式呼吸器一般应具有至少为()的持续工作时间的能力。

A.10min

B.15min

C.30min

考点:教育学油船、化学品船和液化气船油船、化学品船和液化气船题库
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某作家2006年在一家晚报上连载某小说半年,前三个月报社共支付稿酬2000元;后三个月报社共支付稿酬4000元。后因小说反响较大,出版社予以出版,支付该作家稿酬 50000元。作家所获稿酬应缴纳的个人所得税为()元。

A.8960

B.7804

C.6272

D.5430

题型:单项选择题

如图所示,用滑轮组提升重物时,重800N的物体在10s内匀速上升了1m.已知拉绳子的力F为500N,则提升重物的过程中(   )

A.做的有用功是800J

B.拉力F的功率是80W

C.绳子自由端被拉下3m

D.滑轮组的机械效率是60%

题型:单项选择题

仁慈的社会计划者能够通过规定每种产品的价格和数量使社会的总剩余最大。

题型:单项选择题

Some spiders hunt on the ground, others build webs to trap their food, but the grass water spider catches its prey by running along the surface of the water.
This special water spider lives on the grassy banks of streams where mosquitoes, damsel flies and other insects come to feed and breed.
Although it is one of the largest spiders in New Zealand, it has an unusual ability. It doesn’t disturb the water as it waits for its meal, and there is barely a ripple when it skims across the surface at lightning speed to catch its prey.
Grass water spiders deal swiftly with larger insects like damsel flies by pulling their heads under the water and holding them there until they drown.
After a meal, the grass water spider spends up to half an hour grooming itself. It wipes its eight eyes, brushes its antennae, and takes special care to clean the hairs on its body.
It is the hairs that trap tiny bubbles of air so that the spider can run down a blade of grass and stay underwater for up to an hour when it is frightened. The hairs also keep the spider dry, even underwater.
It is only when the female spider is caring for the young that she does not hunt on the water. After mating, she produces a large egg sac, which she carries around for five weeks. Once the eggs start to hatch, she attaches the sac to some blades of grass or a thistle. She then tears the sac open and releases the tiny spiders into the nursery web.

How does the grass water spider kill its prey

A. In a web



B. By drowning
C. By poisoning


D. With its antennae

题型:单项选择题

投资连结保险的基本保险责任()

A.死亡、残疾给付、生存保险领取

B.豁免保险费、重大疾病保险金

C.豁免保费、生存保险金

D.死亡给付、失能保险金

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