a set of keys后加is。a set of keys意為”一串鑰匙“，作主語時(shí)謂語動(dòng)詞用單數(shù)形式is。不能用are。例如：A set of keys is on the desk。桌子上有一串鑰匙。

a set of keys后加is還是are

加is

set of keys 一串鑰匙;一副鑰匙;一套鑰匙

As it happens, I have a spare set of keys in my office. 碰巧我在辦公室有一套備用鑰匙。

My mom gave me a set of keys. 我媽媽給了我一串鑰匙。

A set of keys is on the desk. 有串鑰匙在桌子上。

Stranger: Excuse me, did you see a set of keys? 陌生人：你好，你看到一串鑰匙了嗎?