题目

The young couple would love to have kids, ________, they don’t want to give up freedom. A. such as        B. on the other hand  C. in my opinion  D. for example 答案：B大拖拉机m天耕地a公顷，小拖拉机n天耕地b公顷，大拖机的工作效率是小拖机的工作效率____ 倍 [     ]A ．  B．  C．  D．