Remember that verbs in spanish also have stem changes like E to IE, O to UE and E to I
Entender is one of them, Entiendo,Entiendes, Entiende Entendemos entienden
1- Aprende because la gente is singular
2- Demasida because cervezas is feminine
3- Tiene singular
4- Cometi past tense
6 La gente gorda- feminine no corre
8- el le debe dinero a ella
9 - Los mensajes de sus novios
10- no tengo la capacidad
11 los momentos peores
You're using your english brain with the spainsh grammar and also you have to watch the gender of your nouns
but good luck