The radiation amount of a mobile phone for two half-hour periods per day is equal to ______ to an X-ray for ten seconds.

The radiation amount of a mobile phone for two half-hour periods per day is equal to ______ to an X-ray for ten seconds.

A．expose           B．exposing          C．exposed          D．being exposed

       The radiation amount of a mobile phone for two half-hour periods per day is equal to _______ to an X-ray for ten seconds.

     A. expose          B. exposing      C. exposed          D. being exposed

 The radiation amount of a mobile phone for two half-hour periods per day is equal to ___ to an X-ray for ten seconds.

The radiation amount of a mobile phone for two half-hour periods per day is equal to ______ to an X-ray for ten seconds.

1. A.
   expose
2. B.
   exposing
3. C.
   exposed
4. D.
   being exposed