Upper Intermediate - Global warming

it is too wide the gap between the level intermediate to upper intermediate. my suggestion to you for making a intermediate lesson about economy - stock share, trust found,interest, coins, currency, exchange, bankruptcy,credit, overdraft,hedge fund,investment et cetera. likewise there is missing a lesson about a pice of the new with all the words that involve with the above subject.Thank you very much you are a great guys.

can anyone explain what بات means? I recognise it as the verb to stay over somewhere but not sure what it's function is in either of the two sentences

@d_borthwick this is an interesting question and can be complicated, so I will do my best to simplify it.

The verb (baata بات) could come as a complete verb and it means (he stayed over) or as an incomplete very and it means (became). Don't worry about what complete and incomplete verbs are, but I can give you a hint that (كان, أصبح...) are incomplete verbs and these verbs including (baata) are called (kaana and her sisters كان و أخواتها).
So it's all about the meaning. You can use (baata) as (he stayed over) or even the present tense (yabeet يبيت) which is (he stays over). Examples of that are in the past form (The boy stayed over in the school بات الولد في المدرسة) and in the present form (The boy stays over in his brother's house every Friday يبيت الولد عند أخيه كل جمعة).
The examples of baata being incomplete verb where the meaning is (became) are (بات الولد مريضاً) which is (the boy became ill) and the present form (يبيت الولد عالماً إذا درس) which is (The boy becomes a scholar if he studied).

Hope this simplifies it enough :)

Thanks, Ehab! I had a feeling it worked a bit like that but it makes a lot more sense now. :-)