We should be pleased to send you some samples of our new typewri

We should be pleased to send you some samples of our new typewriter on approval, ______ our own expense.
A、at
B、on
C、for
D、in
【正确答案】：A
【题目解析】：at one's own expense自费
句意：欣寄我方新打字机的样品，供贵方试用，费用自理。