甲烷在氯气中燃烧，可看到集气瓶内壁有黑色固体颗粒生成，瓶口产生大量白雾，根据以上现象分析，上述反应的化学反应方程式为_______________________________。

I’m writing to apologize for my absence from last week’s meeting. I was unexpectedly ________ at work.

A．picked up

B．given up

C．held up

D．made up