(2014·湖南郴州五校第二次联考)Not only________to turn off the lights in the kitchen，but we also failed to lock the front door.

A．we forgot　

B．forgot we

C．did we forget　

D．we did forget

混凝土对粗骨料的最大公称粒径有何要求？在实际工程中有何意义？