Dear Susan,

I'm very gladly to hear you are coming to visit me the next Friday. Unfortunate, I won't be able to meet you at the airport although I have classes in the afternoon. You won't find difficult to get to the city center. The airport bus leaves every 30 minute and will take you rightly to the Friendship Hotel. My classes will be over by then or I will pick you up there. I will take you to a hot pot restaurant for dinner and we'll talk with our plan for the weekend over dinner. Having a pleasant trip and see you Friday.

Yours,

Zhang Ming

在恒容的密闭容器中充入2molA和1molB的气体后发生反应2A（g）+B（g）xC（g），达到平衡后，C的体积分数为m%。若维持容器容积和温度不变，按0.6molA、0.3molB和1.4molC为起始物质的量，达到平衡后，C的体积分数仍为m%。则x的值可能为

A、1            B、2            C、3             D、4