Don’t use your cellphone — we are flying at altitude of 10 000 meters and average speech

问题补充：

Don’t use your cellphone — we are flying at altitude of 10,000 meters and average speech is 678km/h.

A. an; the

B. the; the

C. the; an

D. an; an

答案：

(答案→)A. an; the

B. the; the

C. the; an

D. an; an

解析：句意：不要使用手机—我们现在正在1000米的高空飞翔，平均速度是678km/h. altitude元音音素发音，表示海拔多高时用不定冠词an,第二空用the表示特指飞机的速度，故选A