问题 填空题

电路中有电流的条件一是电路中必须有______,二是电路形成______;我们规定______电荷移动的方向为电流方向(选填“正”、“负”).

答案

有多种形式形成电流,规定:正电荷定向移动的方向为电流的方向;得到持续电流有两个必要条件:一是有电源,二是闭合的电路.

故答案为:电源;通路;正.

选择题
填空题

What’s in a surname You may ask. A new website project has been released, that helps you (1) . Have you ever wondered why your ancestors gathered where they did, or where others with your surname live now A research project (2) in Britain answers these questions. And another study has found the surnames are (3) .
"Smith", for example, remains the most common surname in Britain. Used by (4) people, it has exactly the same concentration it always did in Lerwick, in the Scottish Shetland Islands. "Jones" is (5) , and is the most common among hill farmers (6) .
The data used for this project comes partly (7) . A number of other files are held by Expairing, which is probably Britain’s (8) .
There’ re some of us who are fairly predictable. "Campbell", for example, as you might expect, is somewhat concentrated (9) , and it appears really bizarre to be found anywhere else.
Well, with 25,000 names as (10) , what you can do is put them in general categories, if, for example, you look at (11) . Like the name Webber, you might find it is much more common in the Midlands than (12) . If you go to Wales, most people get their names (13) . And in Yorkshire for example, a lot of people have names (14) that they originally lived in or at least their ancestors did.
Well, we only have 25, 000 names on this website, but there’re (15) now found in Britain and they’ re particularly interesting, for (16) . Most British names are fairly common. And about what we can now do as such is look for (17) from different parts of the world and different faiths, (18) . And what there is in names is actually extremely useful, for researchers in (19) may find a lot about (20) now living in this country.

What’s in a surname You may ask. A new website project has been released, that helps you (1) . Have you ever wondered why your ancestors gathered where they did, or where others with your surname live now A research project (2) in Britain answers these questions. And another study has found the surnames are (3) .
"Smith", for example, remains the most common surname in Britain. Used by (4) people, it has exactly the same concentration it always did in Lerwick, in the Scottish Shetland Islands. "Jones" is (5) , and is the most common among hill farmers (6) .
The data used for this project comes partly (7) . A number of other files are held by Expairing, which is probably Britain’s (8) .
There’ re some of us who are fairly predictable. "Campbell", for example, as you might expect, is somewhat concentrated (9) , and it appears really bizarre to be found anywhere else.
Well, with 25,000 names as (10) , what you can do is put them in general categories, if, for example, you look at (11) . Like the name Webber, you might find it is much more common in the Midlands than (12) . If you go to Wales, most people get their names (13) . And in Yorkshire for example, a lot of people have names (14) that they originally lived in or at least their ancestors did.
Well, we only have 25, 000 names on this website, but there’re (15) now found in Britain and they’ re particularly interesting, for (16) . Most British names are fairly common. And about what we can now do as such is look for (17) from different parts of the world and different faiths, (18) . And what there is in names is actually extremely useful, for researchers in (19) may find a lot about (20) now living in this country.