thE purposE oF thE writEr is________.
A．to suggEst how nEw typE oF hArBor CoulD BE Built At sEA
B．to givE A DEsCription oF A nEw-typE City
C．to DrAw pEoplE' s AttEntion to thE proBlEm oF Air pollution
D．to introDuCE A nEw wAy oF BuilDing hArBor-CitiEs