A set of keys是单数还是复数?

A set of keys是单数还是复数? a set of keys 后用单数还是复数谓语 a set of keys作主语是谓语动词使用单数还是复数 a set of keys 作主语时谓语用单数还是复数? a set of keys 后面的动词用什么形式啊?是单数还是复数啊?还有a pair of 什么的. a set of后面的名词是单数还是复数? Frank,look at that ____是填 a set of keys还是填set of keys this is换he/she is,a set of keys换keys可以吗?为什么a set of keys是复数,下面一句却是is this your set of keys.is不是单数用的吗?什么情况下用at?什么情况下要换第三人称形式?什么单词前面要加the?什么情况 A set of keys谓语动词用单数吗? 是there is a set of keys还是there are a set of keys?is or are 英语短语开头要不要大写,要不要标点 如 是 a set of keys 还是 A set of keys. 是a set of keys还是a set of key?哪个正确? 是where is a set of keys 还是where are 回答是It‘s 还是They're是Is this a set of keys 还是 Are they a set of keys They are a set of keys ,It's a set of keys 哪个是正确的? This set of ...做主语 动词用单数还是复数? I lost a set of keys.然后是用 Is this yours?还是Are these yours? 两串钥匙是two set of keys还是two sets of keys 两串钥匙是two set of keys还是two sets of keys,哪个对?为什么?