是a set of keys还是a set of key?

是a set of keys还是a set of key? A set of keys 是there is a set of keys还是there are a set of keys? There is ( ) A.key B.a set of key C a set of keys D.keys 选哪个 a set of keys please. 求解(a set of keys) 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. I have two __ .A.set of keys B.set of key C.sets of keys D.s a set of ____(key). a set of keys 后用单数还是复数谓语 今天老师跟我们说a set of keys后面用is,后来我们读了一篇短文是这样的：Found:A set of key a set of keys is on the sofa.(on the sofa部分提问）__a set of key