sentences: time is a air & vaccum does not contain oxygen ->  there is no oxygen in space  a human is a kind of animal & an stores is a mean of mankind -> an astronaut is a kind of animal an astronaut is a kind of animal  an white is a mean of plant & an animal requires oxygen to breathe -> an astronaut requires oxygen to breathe an astronaut requires oxygen to breathe  there is no space in time & an astronaut requires oxygen to breathe & spacesuit backpacks contain oxygen -> an astronaut requires the oxygen in a spacesuit backpack to breathe