Mr．Smith has a lot of business _________．I know by _________ that this man cannot be trusted．

A.experience; experience

B.experiences; experience

C.experience; experiences

D.experiences; experiences

答案及解析： A

解析：

本题考查名词的用法。名词experience表示“经验”时，为不可数名词；

表示“经历”时，是可数名词。