VOA慢速英语:Arizona Congresswoman May Owe Life to Luck and 'Battlefield Lessons'

could have been虚拟语气

表示与过去情况相反：主句谓语用“would / could / might + have +过去分词”，从句谓语用过去完成时。
　　　If I had got up a little earlier, I wouldn’t have missed the train.
　　　If I had been more careful, I might have passed that exam.

2.She certainly is following commands.

certainly，naturally，of course，surely
这些副词或词组均有“肯定地，当然”之意。
certainly强调有把握，深信不疑。
naturally指自然而然，毫无造作或天生如此。
of course指毫无疑问，自然如此。可与certainly和naturally换用。
surely表一种必然的可能性，也可表示信心或不轻信。强调主观判断。

3.So you can put pressure on the scalp, which does bleed a lot, to sort of stem that bleeding.

sort of有几分地

例句：I feel sort of queasy
      我有些恶心。

4.In fact, emergency medicine specialist Leigh Vinocur says that specialty grew out of military medicine dating back to World War One.

date back to追溯到…; 从…开始

例句：The castle dates back to the 14th century.
      该城堡建于14世纪。

      The history of the town dates back to the Middle Ages.
      这个城镇的历史可回溯到中世纪。

5.And we have made such great strides, even within this last war, of saving people.

make stride进步

例句：make great strides forwards
      大踏步前进