He says they depend on a limited number of radio wavelengths.

VOA: special.2010.01.26

Remember, there's a limited number of things babies can do.

记住,婴儿们能做的事情有限

耶鲁公开课 - 心理学导论课程节选

"And I don't think that's going to disappear by any finding of a limited review of a relatively-small number of ballots.

VOA: standard.2009.06.29

Under such a program, young drivers are prohibited from nighttime driving, are limited to the number of passengers they can have in their cars at one time and will be ineligible for a full driver's license until they're 18 years old.

VOA: standard.2010.06.24