It means if very unlikely for something to happen, slim chance.
The prisoner is shot because the act of shooting a prisoner is near instantaneous. The action has no duration that would justify the use of the present participle, unless it were an order that had been given and were still to be carried out. Bombing raids over the third reich could go on for hours at a time and be carried on over consecutive nights, so the factories are being bombed. Think of it like this, the decision to shoot the prisoner could be taken, the order given and carried out - and even the mess probably cleaned up - but still during all this while the factories could quite feasibly have been being bombed, continuously, and without respite. Eventually the factories would either cease to exist altogether, or the bombing would cease and the shell-like structures would have simply been bombed.
Hope I can help!
The answer is D: The moon’s surface reflects sunlight.
The moon is Earth´s natural satellite. It is an astronomical body that orbits the Earth in a synchronous rotation with it (that is why we can only see, from Earth, one of its sides, the other being the dark side of the moon). Since the moon, unlike the sun which is a star that produces energy and is, therefore, a light source, it does not shine through its own light, rather it can only reflect upon its surface the sun´s light allowing us to see it with our bare eyes from the Earth.
It's past tense, so the answer is was not
