题干
It was ________ experience that caused the company Robert ________ two years ago to get into trouble .
A：lack of ; set u
B：lacking of ; set u
C：lacking ; pick u
D：being lacked ; started
答案(点此获取答案解析）
A
，
，
与
两数中至少有一个是该数列中的一项，现给出
；
具有性质P，则
