So we have four choices in terms of initial and final energy levels, and also what it means - in terms of the electron -- whether it's gaining energy or whether it's going to be emitting energy?

我们有这四个选项,各有不同的初始能量和末能量,它都是按照电子来说的,不管是失去能量还是得到能量？

麻省理工公开课 - 化学原理课程节选

So this is what he asked them to do: Select four answers to the question 'What should a reader be to be a good reader?' "The reader should belong to a book club."

这就是他要求学生们做的：,从以下四个选项中选取问题,“读者如何才能成为好读者”的答案：,“读者应该是书友会的成员“

耶鲁公开课 - 1945年后的美国小说课程节选