They will usually tell you what gate you should go to, but if you need to ask again, I will provide an example question. Also, you might need to ask someone where the gate is located. 

他们通常会告诉你应该去哪个登机口，但如果你需要再问一次，我将提供一个示例。另外，你可能需要问某人登机口在哪里。

"Which gate did you say it was?"  

你说的登机口是哪个？

"What was the gate number again?" 

登机口的号码是多少，能再说一遍吗？

"Can you point me towards the gate?" 

你可以指给我登机口在哪吗？

"How do I get to the gate again?" 

我怎样才能到达登机口，能再说一遍吗？

"How do I get to gate C2?"  

我怎样才能到C2登机口？

"Where is gate C2?" 

C2登机口在哪？