单选题 This new drug has also helped people to keep doing everyday things ______ longer.
A. of their own B. on their own
C. for their own D. with their own

【正确答案】 B

【答案解析】[解析] of their own他们自己的；on their own他们独立，他们独自；for their own为他们自己；with their own用他们自己的