_________ the help of man-made satellites, we can know what the weather will be like

in the next few days.

________ the help of man-made satellites, we can know what the weather will be like in the next few days．

1. A.
   Under
2. B.
   With
3. C.
   Using
4. D.
   By

_________ the help of man-made satellites, we can know what the weather will be like
in the next few days.