化學題--melting and boiling

As supplementary, under different Pa values / atm. The states of A, B or C varies. So the question must state at room temperature or pressure, or there is no definite solution.

Under room temperature/ 25 degree celsius

A is at liquid state
B is at solid state
C is at gas state

唔該曬兩位解答左我嘅疑難=))
但系我想問,,點解你地兩個有同樣嘅見解呀><
系定論黎架??
可唔可以解釋下牙?
再次多謝兩位X))

No substance has these both melting point and boiling point. But this must be correct:
At room temperature, A is liquid, B is solid & C is gas.

At room temperature, A is liquid, B is solid & C is gas.