除非

Practice 13  (1) Actually, the world’s birth rate is falling. But so is death rate, as medical advances have made it possible for man to live longer than before. Such advances have also reduced baby death rate. (2) Unless population growth is reduced, the

Practice 13  (1) Actually, the world’s birth rate is falling. But so is death rate, as medical advances have made it possible for man to live longer than before. Such advances have also reduced baby d