Three times in recent weeks, Republicans have used parliamentary tactics in the Senate to block the extension of benefits, angering the president at a time when he is trying to move this and other legislation through Congress before the congressional recess.

VOA: standard.2010.07.19

If you never meditate before, this is a wonderful opportunity to do it for the first time.

如果你从没冥想过，这是你们尝试的好机会。

哈佛公开课 - 幸福课课程节选

So, every time you're exposed to a new vaccine or a new antigen you go through this primary response before you have the secondary response.

所以,每当你接触到新疫苗或是新抗原,在再次免疫之前,机体将会经历这样的初次免疫过程

耶鲁公开课 - 生物医学工程探索课程节选