Wang kun : Have you looked at a map?

Wang wei : What did you say just now?

Wang kun : I asked you ______________.

A．whether you have looked at a map

B．whether you had looked at a map

C．whether have you looked at a map

D．whether had you looked at a map

用水蒸汽或其他不燃气体喷射到液面，稀释空气中氧含量，当氧含量低于（）%时，火因缺氧而熄灭。

A、16

B、20

C、23

D、26