They had a mail service, although it was for official use only.

建立了邮政系统，虽然只供官方使用。

耶鲁公开课 - 新约课程节选

You are allowed to use on the test the official version of the Periodic Table of the Elements which most of you should have by now.

在测试中你们可以使用,化学元素周期表的官方版本,你们应该大部分都有了吧。

麻省理工公开课 - 固态化学导论课程节选