可以這樣寫嗎﹖

No...
It is because carbon dioxide (CO2), for oxygen has the oxidation number -2, two oxygen combine with one carbon to form the oxidation number zero compound. So the oxidation number of carbon should be +4.
The number in the blanket is the oxidation number of the former element. So it should be carbon (IV) oxide, but not carbon (II) oxide.

NO CO(II)

應該唔得, 因為係dioxide, 唔係兩個carbon; 點解要咁寫? - CO2嗎!