I’m sorry,a number of books A.is lost B.is missing C.are missing D.are missed .

题目

I’m sorry,a number of books A.is lost B.is missing C.are missing D.are missed .

答案

选C
a number of只是表示数量的定语,修饰复数主语books,系动词要用复数的are,排除A和B
missing是形容词“失踪的、找不到的”,用作表语；而are missed被动语态,意思是“被错过、被遗漏、未被察觉等”,属于词义错误,故排除D.