![](https://cos-cdn.shuashuati.com/pipixue-wap/2020-1230-1107-56/ti_inject-812ce.png)
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 mew way of building harbor-cities