店主们每月都要向这些混混缴纳保护费。

Shop owners had to pay monthly ___protection money to the local thugs.

海关人员对旅客的行李进行了检查。

Customs officers performed a ___search of the passengers' luggage.

新软件上线前，团队进行了彻底的测试运行以确保稳定性。

The team conducted a thorough ___shake-down of the new software before its official launch.