GRE Text Completion: JiJing 1373-GRE填空机经1373题 - SV06L53FH6234820A

Boreal forest is at the southern boundary of the moss-dominated tundra, which remains characteristically treeless because its spongy surface retains water that cannot drain away through the underlying permafrost. But as temperatures rise the permafrost recedes, (i)____________ the (ii)____________ of forest. A. impairing B. renewal C. facilitating D. incursion E. decelerating F. decline