以下哪一个是SDN的关键技术：（）。 A: OpenFlow B: OpenAir C: AirForce D: AirMax

During the war he had tried to ______ in the Royal AirForce, giving his age as eighteen, but had been refused.

The people in the snow-stricken areas need much more food than ______to them by the airforce. A: being delivered B: have been delivered C: delivered D: has been delivered