Observa el Mapa planisferio de la Proyección Mercator y responde. ¿Que es más grande: Groenlandia o China?
¿Qué masa continental es más grande: la del Norte o la del Sur?
¿Qué es más grande Europa o Sudamérica?
Luego verifica tus respuestas con los datos de superficie reales. ¿Qué conclusiones puedes extraer?​

This is all you, but i can give you some topics that you could try. if it rained when you want to do something outdoors, it 'limits' that human activity. maybe you want to do an experiment that goes throughout the whole year and you have to have above freezing the entire year. this 'limits' your activity. i thought of those just off of the top of my head. something that gets to me that might be getting to you is you are thinking too hard about what to do. think simply, and if it is too simple, then bump it up just a little bit.

Well, a and b together would be negative. b alone would also be negative.