大多数交易都是私下进行的。

Most of the deals were made ___behind ___closed ___doors.

影响全世界的决策都是私下制定且高度机密的。

Decisions which affect the whole world are made ___behind ___closed ___doors and are top secret.

谈判是私下进行的。

The negotiations took place ___behind ___closed ___doors.