The reason WHY he made such kind of mistakes is that he has had no previous experience of this kind of job.
The reason THAT he made such kind of mistakes is he has had no previous experience of this kind of job.
选C
The reason WHY he made such kind of mistakes is that he has had no previous experience of this kind of job.
The reason THAT he made such kind of mistakes is he has had no previous experience of this kind of job.
选C