一道英语动词变化题

题目

一道英语动词变化题
Most of these singers so far ------ (see) music as a “job” because it is a good source of making money.
have seen,请给一个详细的解析,
为什么不是seeing,

答案

so far-----到目前为止; 迄今为止
主语Most of these singers“这些歌手中大多数人”
谓语have seen (从过去到现在,用现在完成时)
宾语music