A NASA experimental jet , the X-43A,flew at a world –record speed ---11,260 kilometres an hour on November 17.This speed is ______ as that of sound.

1. A.
   astentimesfast
2. B.
   tentimessofast
3. C.
   tentimesasfast
4. D.
   tentimesfaster

A NASA experimental jet, the X-43A, flew at a world-record speed---11,260 kilometres an hour on November 17. This speed is ____ as that of sound.

A. as ten times fast       B. ten times so fast

C. ten times as fast       D. ten times faster

A NASA experimental jet, the X – 43A, flew at a world – record speed – 11, 260 kilometers an hour. This speed is         as sound.

A．as ten times fast          B．ten times so fast   C．ten times as fast      D．ten times faster