Question

The RiverNile ________ flood large areas, but now its water ________ produceelectricity.

1. A.
   used to; is used to
2. B.
   was used to; is used to
3. C.
   used to; uses to
4. D.
   was used to; is using to

Answer 1

A
used to do 意为过去常常做某事be used to do 为use的被动用法