单项选择题 在中国，1美元=6.3人民币属于（    ）汇率标价方法。 A. 直接标价法 B. 间接标价法

单项选择题 When the general purpose of a speech is to inform, your aim is to ________. A、enhance the knowledge and understanding of your audience B、change the attitude of your audience C、change the actions of your audience D、win over your audience to your point of view

单项选择题 Regarding to the electric dipole, which statement as follows is wrong? A、The electric dipole is composed of a positive charge of  and a negative charge of  , and the positive and negative point charges have separation  , and thus the dipole moment can be expressed as  B、The electric dipole is the name given to two point charges of equal magnitude and opposite sign, separated by a distance that is small compared to the distance to the point  at which we want to know the electric and potential fields. C、The potential arising from a point charge is inversely proportional to the distance  , while that of a electric dipole is inversely proportional to . D、The maximum magnitude of electric field is inversely proportional to .