When the United Nations founded?A. isB. areC. wasD. were

问题补充：

When the United Nations founded?

A. is

B. are

C. was

D. were

答案：

A. is

B. are

(答案→)C. was

D. were

解析：本题的含义是联合国何时被建立，表示的是过去的事件，主语为不可数名词，故用was，故本题选C。