More and more people have come to realize that if we had taken effective measures much earlier, the air quality ______ so seriously now.

A．is not polluted

B．would not be polluted

C．had not been polluted

D．would not have been polluted

（8分）某含氧有机物，它的相对分子质量为74。7.4g该含氧有机物充分燃烧后的产物通过浓硫酸后增重5.4g，通过足量澄清石灰水后有30g白色沉淀生成。求：

（1）该含氧有机物的分子式；

（2）该含氧有机物有多种同分异构体，写出其中能水解的同分异构体的结构简式