Question

1. Fill in the blanks using a word.

Passenger airplanes mostly fly (a) _______ speeds less than that (b) _______ sound. Airplanes (c) _______ can fly (d) _______ greater speeds have been built. This is (e) _______ if they fly (f) _______ speeds greater (g) _______ the speed of sound, (h) _______ fuel consumption increases enormously
USING HINTS
at, of,because
the, at, than, at, which​

Answer 1

Answer:

1. at,because 2.which,than