he always made his best?

当然是do对了,这是一个习语：Do one's best,意思是竭尽全力的意思,这种句子一定要死记硬背的,这和咱们汉语的习惯相悖,所以不能完全用理解来掌握
类似的习语还有try one's best,or do sth to the best of one's ability等等