a grovelling letter of apology的用法和样例：
- We received a letter of apology.
- He wrote a letter of apology to the hostess.
- She wrote a letter of apology but only under protest.
- A letter of apology will be sent to Mr.Yu from our Customer Ombudsman,” said McCarney-Warus.
- Li Ming is writing a letter of apology because he gathered together a group of people and ran riot.