根据人教新目标版九年级英语unit11《Could you please tell me where the restroom》完成下列句子，每空词数不限。
1. It is a very common and necessary activity to _____________.
2. Knowing _____________ is important.
3. We should change _____________we speak when talking with different people.
4. The expressions you use might depend on ___________ you are speaking to or __________ you
know them.
5. If you stop a stranger in the street, we might first say "Excuse me. __________" or "I'm sorry to
trouble you but," before asking them for help.