The first step uses a bit of influenza DNA to get the patient's immune system to begin fighting off the flu, and then the protection is given a "boost" some time later by the second step, which can be either another bit of DNA or a conventional flu vaccine.

VOA: standard.2010.07.21

Then the first time so he came up a major third there and then quickly backed off with just a half step below it, which completely gave it a different feel.

于是开始的时候,乐曲中出现一个大三和弦,然后快速地降低了半个音,这种变化给人完全不同的感受

耶鲁公开课 - 聆听音乐课程节选