第15题: [单项选择]What can you do if you are not sure about the postage A. You can buy stamps from machines. B. You can buy different stamps of different prices. C. You can ask the clerk for help. D. You can put more stamps on the envelopes. 参考答案:C 答案解析:A项错误,这是在知道所需邮资的情况下做的;B、D两项均不合事实;C为正确答案,即:你不知道你的邮件需多少邮资时,可问邮局职员。