单选题 _____ his work, he would do it till it was finished.
  • A) Once Charles would start
  • B) Once Charles started
  • C) Since Charles would start
  • D) Since Charles started


【正确答案】 B
【答案解析】[解析] once意为“一旦……就……”，主句为将来时，时间状语从句不用将来时，而用现在时或过去时表示将来或过去要发生的动作，故选B。since的意思是“自从”或“由于”，与题意不符。