A．People should cut down their consumption.
B．Developing countries should make greater effort.
C．The world should realize the problems and set policies.
D．A family should have three children at most.
A．It is very explosive in social temps.
B．It should be a universal law for all countries.
C．It should consider the actual situation.
D．It should be compulsory and be spread to all parts of the community.
A．The strips of a special plant.
B．Wood or the bark of trees.
C．Worn-out cloth and straw.
D．Some common chemicals.