It says catheters should be used only if necessary.

VOA: special.2010.04.21

In very severe cases, it can even defile some common objects, and in those cases, the source of impurity might have to be isolated or excluded if necessary.

在一些非常严峻的情况中，它会玷污一些普通的事物，在这种时候，不洁之源,也许只能被孤立，严重的话需要驱逐。

耶鲁公开课 - 旧约导论课程节选

Very difficult problems, but in my judgement, all solvable if we generate the country in the kind of bipartizan political cooperation and political courage that will be necessary to fix them.

这些问题很不容易解决，但我认为,不是不能解决，只要我们,以这种两党制的合作形式治理国家,还要有治理它们的政治勇气。

普林斯顿公开课 - 国际座谈会课程节选

"We can,if necessary, be very centralized,"

VOA: standard.2009.09.24