【单选题】墨卡托方位法把世界划分成了()个区域,提高了地理位置的精确性。
【多选题】下列有关交流磁路,说法正确的是( )。
A.
在磁化曲线非线性的影响下,当电源电压为正弦量时,并励线圈的电流有可能为非正弦量
B.
在磁化曲线非线性的影响下,当电源电压为正弦量时,串励线圈的电流有可能为非正弦量
C.
在磁化曲线非线性的影响下,当线圈电流为正弦量时,并励线圈两端的电压有可能为非正弦量
D.
在磁化曲线非线性的影响下,当线圈电流为正弦量时,串励线圈两端的电压有可能为非正弦量
【单选题】The El Nino ('little boy' in Spanish) that pounded the globe between the summers of 1997 and 1998 was in some measure the most destructive in this century. Worldwide damage estimates exceed £ 20 billi...
A.
the normal westward trade winds weaken
B.
the normal eastward trade winds weaken
C.
the normal westward trade winds strengthen
D.
the normal eastward trade winds strengthen
【判断题】在静电场中电力线不是闭合的曲线, 所以在交变场中电力线也是非闭合的曲线。
【单选题】A hand held instrument used to measure distances between objects and the ship is a ______.
【单选题】The Columbia University researchers studied the relationship between the past El Nino occurrences and sea-surface temperatures.
【单选题】要求元件焊接人员操作时必须离焊接点至少( )以上,以免吸入焊锡丝融化所产生的有害物质,并打开排风装置。
【单选题】两直径不等的圆柱与圆锥正交时,相贯线一般是一条 曲线。
【单选题】Although one accountant mistakes to write down a credit sale as a cash sale, the figure on the debit side of the trial balance is right.