题目

电场强度的定义式为，下列说法正确的是 A. 这个定义式只适用于点电荷的电场B. E的大小与F成正比，与q成反比C. 移去电荷q，E的大小变为零D. E跟检验电荷q无关 答案：【答案】D【解析】A、电场强度的定义式为，采用比值法定义，适用于任何电场，故A错误；BCD、E是由电场本身决定的，与检验电荷无关，不能说E的大小与F成正比，与q成反比，当移去电荷q，E的大小不变，故D正确，B、C错误；故选D。change,in, dictionary,become,while,express,great,nearly,answer,everyday    As we all know,there are some differences between American English and.British English. How did these differences take place? There is no quick (81) to this question.   Actually at first the language in Britain and America was the same. After America (82) an independent country,the language gradually began to change. For a long time the language in America stayed the same, (83) the language in Britain changed.   Over the centuries,a number of words and expressions disappeared in British English,though they are still in (84) use in America. For example,Americans still use the (85) “I guess”(which means “I think”) , just as the British did 300 years ago.   In 1828 Noah Webster published the first American (86) . To make American English different from British English,he (87) the spelling of many words. That’s why the words “colour”，“centre” and “traveller” are spelled “color”， “center” and “traveler” in American English. Except for these differences in spelling,written English is (88) the same in both British English and American English.   The differences are much (89) in spoken language. However,most of the time people from the two countries have no difficulty (90)understanding each other.