There was great excitement on the planet of Venus  this week. For the first time Venusian scientists managed to land a satellite on the planet Earth, and it has been sending back signals as well as photographs ever since. The satellite was directed into an area known as Manhattan (named after the great Venusian astronomer Prof. Manhattan, who first discovered it with his telescope 20 000 light years ago).Because of excellent weather conditions and extremely strong signals, Venusian scientists were able to get valuable information as to feasibility  of a manned flying saucer  landing on Earth.A press conference was held at the Venus Institute of Technology. "We have come to the conclusion,based on last week's satellite landing," Pro. Zog said,"that there is no life on the Earth." "How do you know this?" the science reporter of the Venus Evening Star asked.  "For one thing, Earth's surface in the area of Manhattan is composed of solid concrete and nothing can grow there. For another, the atmosphere is filled with carbon monoxide  and other deadly gases and nobody could possibly breathe this air and survive." "What does this mean as far as our flying saucer program is concerned?" "We shall have to take our own oxygen with us, which means a much heavier flying saucer than we originally planned. " "Are there any other hazards that you discovered in your studies?" "Take a look at this photo. You see this dark cloud floating over the surface of Earth? We call this the Consolidated Edison Belt. We don't know what it is made of, but it could give us a lot of trouble and we shall have to make further tests before we send a Venus Being there." "If what you say is true, won't this set back the flying saucer program several years?" "Yes, but we shall proceed as soon as the Grubstart gives us the added funds." "Prof. Zog, why are we spending billions and billions of zilches to land a flying saucer on Earth when there is no life there?" "Because if we Venusians can learn to breathe in an Earth atmosphere, then we can live anywhere." The "dark black cloud" on the photograph refers to  _  .
the polluted air floating over the surface of Earth the mass of tiny drops of water floating above Earth the things that are unknown to everybody the dark clouds gathering before a storm breaks