On account of the development of theeconomy, the environment is seriously polluted and we must ________ the emission of the carbon dioxide. [ ]

smart, handsome, considerate andhumorous, ______, I can’t speak too highly of him

____ my opinion, American eat too much meat

The guard keeps watch at the gate.—So he does. Only those knows well could be let in.

We should pay more attention ______teenage problems.