But more than these kinds of natural processes are needed to have an atmosphere. You also need gravity. Without sufficient gravity, any gases will just leak out into space and be gone. Earth loses some of its atmosphere this way, but in general it has enough mass to hold on. The moon, on the other hand, with only one-sixth the gravitational pull of earth, isn't big enough to do the job. Still, recent observations have shown that the moon does in fact have an atmosphere of its own. It's so thin, however, that it only counts as one in technical terms, and certainly couldn't be breathed. So much for that restaurant.
n. 块,大量,众多
adj. 群众的,大规模