根据外交礼仪，大使抵达时必须遵循正式的欢迎程序。

According to diplomatic ___protocol, the ambassador must follow a formal welcome procedure upon arrival.

蓝牙协议让无线设备之间能够互相通信。

The Bluetooth ___protocol enables wireless devices to communicate with each other.

两国签署了新的贸易协议。

The two countries signed a new trade ___protocol.

实验室必须严格遵守实验方案以确保结果的准确性。

The lab must strictly follow the ___protocol to ensure accurate results.