把某物限制在一定规模内

keep to sth. cut down to size size down keep down keep sth. secret keep to keep one's voice down water sth. down keep sb. going in sth. down to to get down to keep sth. a secret from sb. keep to sth. cut down to size come down to sth guarantee to keep sth. in good repair keep down size down down size keep to keep sth intact keep sth in abeyance keep sth underfoot