"The lack of access is also affecting the ability of the Afghan population to obtain the necessary medical assistance and basic services, which they need,and which they are increasingly not getting,"

VOA: standard.2009.08.07

Why don't bacteria need a distinct nucleus and that's necessary in a human cell?

为什么细菌不需要单独的细胞核,而对人类细胞则为必需

耶鲁公开课 - 生物医学工程探索课程节选

adaptations,coastal protections Among a host of necessary need to be built, crops threatened by drought need to be modified, health care needs to be stepped up, and new clean energy solutions need to put in place.

VOA: standard.2009.12.11

"That is why I will send our servicemen and women into harm's way only when it is necessary and ensure that they have the training and equipment they need when they enter the theater of war,".

VOA: standard.2009.05.23

"It is a promise that as long as I am your Commander in Chief, I will only send you into harm's way when it is absolutely necessary, and with the strategy, the well-defined goals, the equipment and the support you need to get the job done,"

VOA: standard.2009.05.22