桌子上放着两封信。

There are two ___letters on the table.

我每周都会给奶奶写一封信。

I write a ___letter to my grandma every week.

他只是遵守了合同文字上的规定，但没有考虑背后的精神。

He only followed the ___letter of the contract without considering its underlying spirit.

他名片上的字母'MBA'代表工商管理硕士学位。

The ___letters 'MBA' on his business card stand for Master of Business Administration.