在以接地电流入地点为圆心，多少米范围半径内行走的人，两脚之间承受跨步电压（）。 1000。 100。 50。 20。
产品策划是生产企业农化服务的主要职责
Camping
Camping wild is a wonderful way to experience the natural world and， at its best， it makes little environmental influence. But with increasing numbers of people wanting to escape into the wilderness， it is becoming more and more important to camp unobtrusively （不引人注目地） and leave no mark.
Wild camping is not permitted in many places， particularly in crowded lowland Britain. Wherever you are， find out about organizations responsible for managing wild spaces， and contact them to find out their policy on camping and shelter building. For example， it is fine to camp wild in remote parts of Scotland， but in England you must ask the landowner's permission， except in national parks.
Camping is about having relaxation， sleeping outdoors， experiencing bad weather， and making do without modern conveniences. A busy， fully-equipped campsite （野营地） seems to go against this， so seek out smaller， more remote places with easy access to open spaces and perhaps beaches. Better still， find a campsite with no road access： walking in makes a real adventure.
Finding the right spot to camp is the first step to guaranteeing a good night's sleep. Choose a campsite with privacy and minimum influence on others and the environment. Try to use an area where people have obviously camped before rather than creating a new spot. When camping in woodland， a void standing dead trees， which may fall on a windy night. Avoid animal runs and caves， and possible homes of biting insects. Make sure you have most protection on the windward side. If you make a fire， do so downwind of your shelter， always consider what influence you might have on the natural world. Avoid damaging plants. A good campsite is found， not made — changing it should be unnecessary.
Wild camping is always permitted in many places.（） True。 False。 Not Give。
某企业2000年投资收益的概率分布如下：
2000年，企业资金总额为500万元，其中借入资金与自有资金的比例为1∶4，企业所得税税率为33％，借入资金利息率为10％。（对于除不尽的数，请保留小数点后两位）
计算该企业2000年期望的税息后自有资金收益率。
电气设备的（）与电器的额定绝缘电压或工作电压、污染等级和绝缘测量组别有关。 爬电距离。 对地距离。 漏电起痕。 电气间隔。
教育目的的对整个教育工作具有导向作用、激励作用和（）
