I guess formal and informal refer to two types of essay - you can write a formal essay where you avoid conversational language and such and where you need to be very professional, or you can write informally where you don't have to think about such things, it is very casual.
Before 900; (noun) Middle English; Old English caru, cearu, cognate with Gothic kara, Old High German chara “lament”
1. Gives
2.teaches
3.brings
4. Wore
5.controls
6.starts
7. Do, Believe
8.works
9.opens
10.makes
11.watches
12. Brush
I know all the answers but try to do the rest yourself