English Thread

In this thread, we attempt to learn to read, write, and speak English, a language which would be very useful to know. It is widely spoken throughout the world.

Do you speak English? Are you fluent? What resources did you use to learn? Can you give some examples in this thread? Posts some useful links.

Let's help each other out and learn a new language.

Ok. Two cases.
1) I'm in a room and talking to a friend on the phone. The friend don't know that there's only one chair in the room. I want to start a conversation saying "I'm going to sit on (a/the) chair". What article should I use?
2) I'm in a room with my friend and he sees and knows that there's only one chair in the room. I want to start a conversation saying "I'm going to sit on (a/the) chair". What article should I use?