Welcome, and how is Chengdu today?
when people turned on too many lights in a room,
if i want to complain, is it correct to say: "it is too bright", Yes, you can say 'It's too bright in here.' if you mean there is too much light.
also, is there any other way to express this complaint? Here you need the noun 'complaint'.
You can just say that 'there are too many lights on', but that may be taken to mean that you think electricity is being wasted.