21. rise in carbon dioxide is causing steady increase in global warming.
A. The; a B. 不填; a C. The; 不填 D.A；the
22.-Sorry, I couldn’t find the suitable shoes you need.
- .
A. Thanks anyway B. No problem C. Don’t mention it D. It’s all the same
23.Have you considered how weak humans are a volcano, hurricane or earthquake?
A. comparing with B. compared with
C. to compare with D. having been compared with
