Planting them every two or three weeks would provide a continuous harvest into the fall.

VOA: special.2009.02.17

We have the Harvard-Yale football game every fall,

每年秋天我们有哈佛—耶鲁橄榄球赛，

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If this was tetanus, you got this tetanus vaccine when you were young; you get a boost every five or ten years because your antibody levels are starting to fall.

以破伤风为例,小时候,你接种过破伤风的疫苗,每隔五年或十年要再接种一次,这是因为体内的抗体浓度会下降

耶鲁公开课 - 生物医学工程探索课程节选

Planting them every two or three weeks will provide a continuous harvest into the fall.

VOA: special.2010.03.02

"We needed rain yesterday,right,". "We needed rain most probably a fortnight ago for our crops to realize their full potential but most probably been 30 percent of our yield potential gone and every day it doesn't rain that will fall quite dramatically from there."

VOA: standard.2009.09.03