一对标准直齿圆柱齿轮传动，m=5mm，z1=20，z2=100，中心距a=( )。

以下哪项不属于公众参与城市规划的具体形式（）

A.听证会

B.集会活动

C.规划展览

D.民意调查

So you’ve got an invention — you and around 39,000 others each year, according to 2002 statistics!

The 64,000-dollar question, if you have come up with a device which you believe to be the answer to the energy crisis or you’ve invented a lawnmower which cuts grass with a jet of water (not so daft, someone has invented one), is how to ensure you’re the one to reap the rewards of your ingenuity. How will all you garden shed boffins out there keep others from capitalizing on your ideas and lining their pockets at your expense

One of the first steps to protect your interest is to patent your invention. That can keep it out of the grasp of the pirates for at least the next 20 years. And for this reason inventors in their droves beat a constant trail from all over the country to the doors of an anonymous grey-fronted building just behind London’s Holborn to try and patent their devices.

The building houses the Patent Office. It’s an ant heap of corridors, offices and filing rooms—a sorting house and storage depot for one of the world’s biggest and most varied collections of technical data. Some ten million patents — English and foreign — are listed there.

File after file, catalogue after catalogue detail the brain-children of inventors down the centuries, from a 1600’s machine gun designed to fire square bullets at infidels and round ones at Christians, to present-day laser, nuclear and computer technology.

The first letters’ patent were granted as long ago as 1449 to a Flemish craftsman by the name of John Utynam. The letters, written in Latin, are still on file at the office. They were granted by King Henry Ⅵ and entitled Utynam to import into this country his knowledge of making stained glass windows in order to install such windows at Eton College.

Present-day patents procedure is a more sophisticated affair than getting a go-ahead note from the monarch. These days the strict procedures governing whether you get a patent for your revolutionary mouse-trap or solar-powered back-scratcher have been reduced to a pretty exact science.

From start to finish it will take around two and a half years and cost ￡ 165 for the inventor to gain patent protection for his brainchild. That’s if he’s lucky. By no means all who apply to the Patent Office, which is a branch of the Department of Trade, get a patent.

A key man at the Patent Office is Bernard Partridge, Principal Examiner (Administration), who boils down to one word the vital ingredient any inventor needs before he can hope to overcome the many hurdles in the complex procedure of obtaining a patent — "ingenuity".

People take out a patent because they want to（）

A．keep their ideas from being stolen

B．reap the rewards of somebody else’s ingenuity

C．visit the patent office building

D．come up with more new devices

（4分）如图为NaCl、KNO₃的溶解度曲线，回答下列问题：

（1）20℃时，KNO₃的溶解度是　         g。

（2）某实验小组进行以下实验：

10 g水  X  Y  Z

X、Y、Z中为饱和溶液的是　          。

（3）把NaCl的不饱和溶液变为饱和溶液，下列方法中一定可行的是               （填序号）

A．降低温度      B．加入NaCl固体     C．蒸发溶剂

（4）提纯KNO₃中混有少量的NaCl 可采用         方法

制图题：画出两相式方向过电流保护原理及展开图。

运动员赛前应多吃牛肉、薯类等食品以补充热量提高体力。