根据所给提示，完成句型转换，每空一词，含缩略词。
(1)Tom won't visit the farm. He'll stay at home. (同义句)
Tom will stay at home ____ ____ visiting the farm.
(2)This dress cost her 100 yuan. (改为一般疑问句) 
____  this dress____  her 100 yuan?
(3)London held the first World Expo in 1851. (对划线部分提问)
____  did London____  the first World Expo?
(4)请安静，我将给大家分发试卷。（完成译句）
Be quiet, please. I'm going to____ ____  your test paper.

用一条绝缘轻绳悬挂一个带电小球，小球质量为1.0×10^﹣2kg，所带电荷量为+2.0×10^﹣8C，现加一水平向右的匀强电场，平衡时绝缘绳与铅垂线成30°夹角，求这个匀强电场的电场强度．