—When does our class meeting begin?

—Oh, it’s been _____ because of the sports meeting.

A．put away

B．put off

C．put down

D．put out

屋面防水等级为Ⅳ级，设防道数为一道设防，选用高聚物改性沥青防水涂料时，其厚度应为≥2mm。( )