Now is the time to deliver on health care." The president said reform proposals which he estimates would cost would provide security and stability to the insured, and make it possible for tens of millions of Americans who are not to get affordable insurance through a proposed exchange system in which private companies would compete.

VOA: standard.2009.09.10

One class of them is beta-blockers, they bind to beta-adrenergic receptors, which are receptors that exchange information between your nervous system and the contractile system that beats your heart and that causes the heartbeat.

一类药物是β阻断剂,它们与β肾上腺素受体结合,这种受体能够在神经系统和,控制心跳的心肌收缩系统之间传递信息,从而产生心跳

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