Federal health minister,Nicola Roxon, says forcing the vessel to cancel a planned 10-day trip around the Great Barrier Reef is a necessary precaution.

VOA: standard.2009.05.30

Why should we think there's some--Even though, normally, the barrier can be crossed and Xs can study the non-X, why should that barrier suddenly become un-crossable in the particular instance when we're dealing with Platonic forms?

为什么我们应该认为即使通常来说,那个界限是可以跨越的,即X可以研究非X,那为什么这个界限突然,在讨论柏拉图型相的时候,就变得不可逾越了呢

耶鲁公开课 - 死亡课程节选

a 15-kilometer-wide barrier of trees that would cross 11 countries and halt the spread of the Sahara.

VOA: standard.2010.04.01

"And their struggle and barrier is having an adequate health workforce and facilities for the kind of high-tech things that happen to mothers that are at risk " In contrast,Boufford says developed nations have excellent medical technology.

VOA: standard.2010.06.23