My uncle is a writer. He ______ many books since he was young.
--- What’s your family rules? --- We shouldn’t talk ____ food in our mouths while having meals.
--- What’s the matter, Mary? You looked upset.--- I failed again in my math exam. I’m really sorry because I don’t want to ____ my parents down.
--- Do you have any plans for this weekend?--- I’m not sure. I _____ go climbing Mount Baoshi.
The world’s population is growing ______, and there is ____ land and water for growing rice.
Lincoln came from nothing, yet but he did ____ that changed the world.