如图甲所示,为测定物体冲上粗糙斜面能达到的最大位移x与斜面倾角θ的关系,将某一物体每次以不变的初速度大小v0沿足够长的斜面向上推出,斜面底边固定在水平地面上,调节斜面与水平方向的夹角θ,实验测得x与斜面倾角θ的关系如图乙所示,物体受到的最大静摩擦力等于滑动摩擦力,g取10 m/s2,根据图象可求出( )
A.物体的初速度大小v0=6 m/s
B.物体与斜面间的动摩擦因数μ=0.6
C.取不同的倾角θ,物体在斜面上能达到的位移x的最小值xmin=1.44 m
D.当θ=30°时,物体达到最大位移后将沿斜面下滑
For career(职业) changers thinking about growth and advancement potential, forget the blue-collar and white-collar categories: Green is the way to go. According to Bracken Hendricks, a senior fellow at the Center for Global Progress, careers that promote environmental responsibility will become main stream within a decade. “The growth in green careers will be like the Internet boom, which not only created new jobs, but also had an influence on the overall economy(经济),” he says.
The increasing environmental problems and need for eco-friendly products and services are creating a new job section of green-collar jobs. Many countries of the world have realized the importance and need for energy-saving products and services. It is expected that by 2025 about 25% of the jobs in developed countries will be of green-collar jobs. Doesn’t the data look promising for the future?
Green-collar jobs have become a bright career chances for all. And jobs will pop up at every income level, from environmental manager to gardener. For example, many countries including the United States have understood that fossil fuels have negative effect on the environment which can later become a serious danger to mankind. As a result, possibilities are being explored to find alternatives to satisfy demands in a better way. The increasing demand of newer resources(资源) has creating the need for experts and researchers who can find better ways to deal with the ongoing needs. In addition, in order to meet the increasing demands of environment-friendly equipment, both green product designer and educated and trained workers are needed. Management of environmental organizations also demands a large number of environmental managers.
Where can you find green-collar jobs? Internet is undoubtedly the best way to find information on almost any matter. Nowadays, different kinds of jobs are being posted online. Search through a couple of job websites to look for a bright future in energy conversion and recycling of waste management. Check regularly and find the right work for yourself. People who read newspapers can also find different kinds of green-collar jobs.
67. Why does Bracken Hendricks mention the Internet Boom in Paragraph One?
A. To explain the importance of technology.
B. To provide evidence of his recent research.
C. To indicate the bright future of green careers.
D. To inform us of the way of finding green-collar jobs.
68. Which of the following probably creates green-collar jobs?
A. Promoting services.
B. Training employees.
C. Consuming fossil fuels.
D. Developing new resources.
69. What is mainly talked about in Paragraph 3?
A. The requirements for green employees.
B. The development of the green industry.
C. The economic influence of green careers.
D. The job chances in the environmental industry.
70. The passage is written to _______.
A. discuss eco-friendly services
B. introduce promising career chances
C. suggest ways of saving energy at work
D. explain the best method of finding jobs
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P(K2≥K) | 0.050 | 0.010 | 0.001 |
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1970年成功发射的“东方红一号”是我国第一颗人造地球卫星,该卫星至今仍沿椭圆轨道绕地球运动.如图所示,设卫星在近地点、远地点的速度分别为v1、v2,近地点到地心的距离为r,地球质量为M,引力常量为G.则
A. B.
C. D.
________ (luck), native English speakers can understand each other even if they don't speak the same kind of English.
(2019·泰安二模)酸奶是经乳酸菌发酵处理的奶制品,口感好、营养价值高,是乳糖不耐受人群的理想之选。回答下列问题:
(1)制作酸奶,获取优良菌株很关键。筛选的原理是____________________________________。
(2)酸奶制品厂收购牛奶时,会严格检查是否含有抗生素,这样做的目的是________________。
(3)酸奶制作时,常采用______________________法杀菌,而不采用高压蒸汽灭菌法,原因是_______________________________________________________________________________。
(4)奶制品包装上常见“胀袋勿食”标识。胀袋发生的原因__________(填“是”或“不是”)乳酸菌大量繁殖导致的,试写出你的判断依据:_______________________________________。