If I short the one-period bond it cancels out, so I've made no net purchase in 1925.

卖空一单位一年期债券则刚好抵消,所以我在1925年的净买入为零

耶鲁公开课 - 金融市场课程节选

And, one thing I'd like to add to it, and that is, and I told this to my recitation sections that when you do these quizzes, in spite of the fact that it might be trivial in some cases, make sure you carry the units through.

而我要在这基础上再加一条，我在我的背诵课上也讲过,当你考试时，尽管单位不重要，但我希望你能注意它们。

麻省理工公开课 - 固态化学导论课程节选