Global warming is called (to call) the greenhouse effect because the

Global warming
is called
(to call) the greenhouse effect because
the gases above the earth make the planet comparable to a greenhouse.
2)
The term acid rain refers to what scientists call acid deposition. It
(to cause) by destructive airborne acidic pollutants.
3)
Acid rain
(to discover) in 1852, when the English
chemist Robert Agnus invented the term.
4)
Recently, a more intensive research on the true causes of acid rain
(to do) so that countries have the information they
need to prevent acid rain and its dangerous effects.
5)
Air pollution can
(to find) both outdoors and indoors.
6)
Every year, 14 billion pounds of sewage, sludge, and garbage
(to dump) into the worlds oceans.