图示电路中a、b端的等效电阻Rab在开关K打开与闭合时分别为（）。 ["10、10","10、8","10、16","8、10"]
简述扦插繁殖特点
You （）him so closely; you should have kept your distance． ["shouldn’tfollow","mustn’tfollow","couldn’t have been following","shouldn’t have been following"]
标定KMnO4溶液时，滴定温度是（） ["75~85℃","65~75℃","85~95℃","55~65℃"]
复合杠杆
助溶剂的作用是什么？
