应该把down去掉.这句话的意思是妈妈从灌木丛上剪了一些话,所以用cut就可以了.这是cut down的用法：
1.削减
He tried to cut down on smoking but failed.
他试图少抽烟,但没成功.
2.缩短
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.
3.砍倒