13. Have you stamped the letter with the right postage?
你贴邮票的邮资对吗？
还能这样说：
Has this letter been stamped with correct postage?
Have you put correct stamp on the letter?
应用解析：
with a stamp of impatience 不耐烦地一跺脚；
the stamp of the age 时代的特征；
bear the stamp of suffering 带有受苦的痕迹
14. I didn't mail the letter to her, because I didn't have her address.
我没有把那封信寄出，因为我没有她的地址。
还能这样说：
I didn't post the letter for lacking of her address.
I failed to mail the letter for I didn't know where she lived.
应用解析：
letter of recommendation 推荐书；介绍信；
letter of reference 调查信；保证书；
letter of regret 致歉信
15. Your letter is 30 grams overweight.
你的信超重30克。
还能这样说：
Your letter weighs over 30 grams in excess of the allowance.
The excess weight of your letter is 30 grams.
16. What is the postage of this letter, please?
请问这封信的邮资是多少？
还能这样说：
How much should I pay the postage of this letter?
How much is the postage of this letter?
谚语：
Don't put off till tomorrow what should be done today.
今日事，今日毕。
17. It will take only about 6 days to Beijing.
大概6天就能到北京了。
还能这样说：
Your friend may receive your letter in about 6 days.
It needs about 6 days to Beijing.
应用解析：
reach one's hand 伸出手；
reach sb. sth. 递给某人某物；
reach sb. a kick 踢某人；
reach toward sth. 伸向某物