题目

Jane nearly missed the flight ____ doing too much shopping. A. as a result of    B. on top of     C. in front of     D. in need of 答案：A有甲、乙两根电阻丝，若把甲电阻丝单独接在某电源上烧开一壶水需10min；若把乙电阻丝单独接在同一电源上并烧开同样一壶水需30min；那么把这两根电阻丝串联和并联接在同一电源上并烧开同样一壶水时，串联需    min；并联需    min．