十万火急的英语问题thedoctoradvisedhimtocutdownondrinking为什么用cutdown,而不是CUTOFF?

the doctor advised him to cut down on drinking
医生建议他减少喝酒
cut down削减缩短
He tried to cut down on smoking but failed.
他试图少抽烟,但没成功.
Cut down the article so as to make it fit the space available on the paper.
把文章缩短一些,这样就能排进报纸有限的版面中.
切除切断;中断
He had a finger cut off by a machine while working.
他在工作时被机器切掉了一个手指.
I was cut off on my line to London.
我打伦敦长途时,电话线被切断了.