During World War I, the federal government nationalized all the express companies.

VOA: standard.2010.03.11

And Born worked on a number of things, including the Born exponent, and taught himself crystallography sort of as something to do during World War I.

玻恩也做出了许多贡献，包括玻恩指数，他自学结晶学,这大约是在一战期间。

麻省理工公开课 - 固态化学导论课程节选

A majority of scholars and historians agree that the massacre of an estimated one million Armenians during World War I constitutes genocide as defined by the 1948 United Nations Convention on Genocide.

VOA: standard.2010.03.19