–Why do you look so sad?

-Bad luck! I made some mistakes in the test. I was not ___________.

A．enough careful

B．enough careless

C．careful enough

D．careless enough

在可以使用燃煤的区域，属于不环保使用燃煤行为的是（）。

A.选用优质燃煤

B.使用固硫型煤

C.安装除尘脱硫设施

D.使用低质含硫煤