1. 어법

Some (optimistic/pessimistic) scientists believe (what/that) climate change on Earth has already passed the 'tipping point' (which/beyond which) it is not possible to stop the slide into global meltdown. But other groups of scientists think that even if the tipping point has been and gone there might still be hope for the planet in the form of geo-engineering, (where/which) is superscale design-and-build work that could reverse the effects of climate change. The ideas (putting/put) forward include sending giant sunshades into space to block out some of the Sun's light; building a network of industrial plants around the globe that would suck in carbon dioxide, compress (them/it) into liquid, and then pump it underground; and (tip/tipping) gallons of fertilizer into the oceans to encourage the growth of marine plant life (absorbing/to absorb) carbon dioxi de from the air by photosynthesis.