下列“线型遗产”被列入《世界遗产名录》的是（） A.丝绸之路 B.长城 C.京杭大运

静电场方向平行于x轴，其电势φ随x的分布可简化为如图所示的折线．一质量为m、带电量为+q的粒子（不计重力），以初速度v₀从O点进入电场，沿x轴正方向运动．下列叙述正确的是（　　）

A．粒子从O运动到x₁的过程中，电场力做正功

B．粒子从x₁运动到x₃的过程中一直加速

C．要使粒子能运动到x₄处，粒子的初速度v₀至少为2

D．若v₀=2

建设工程项目施工成本偏差是指( )之差。

A．已完工程实际施工成本与拟完工程计划施工成本

B．已完工程计划施工成本与拟完工程计划施工成本

C．已完工程实际施工成本与已完工程计划施工成本

D．已完工程计划施工成本与拟完工程实际施工成本

焦耳定律：Q=KI^2RtK为多少（）

A.0.20

B.0.21

C.0.23

D.0.24

     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, avoid 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 downivind

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.

1. You needn't ask for permission when camping___________.      

A. national parks in England      

B. most parts of Scotland      

C. crowded lowland Britain      

D. most parts of England

2. The author thinks that a good campsite is one_________.    

A. with easy access    

B. used previously    

C. with modern conveniences    

D. far away from beaches

3. The last paragraph mainly deals with__________.    

A. protecting animals    

B. building a campfire    

C. camping in woodland    

D. finding a campsite with privacy

4. The passage is mainly about___________.    

A. the protection of campsites    

B. the importance of wild camping    

C. the human influence on campsites    

D. the dos and don'ts of wild camping

锈菌主要寄生危害寄主的哪部分，引起多种植物锈病。（）

A、茎叶

B、花果

C、种子

D、根部