Years ago we didn't know this, but recent science ______ that people who don't sleep well soon get ill.

A. showed              B. has shown        C. will show         D. is showing

Years ago we didn’t know this, but recent science _______ that people who don’t sleep well soon get ill.

A. showed       B. has shown        C. will show        D. is showing

Years ago we didn't know this, but recent science ______ that people who don't sleep well soon get ill.

  A. showed              B. has shown        C. will show         D. is showing

Years ago we didn’t know this, but recent science ______that people who don’t sleep well soon get ill.

Years ago we didn’t know this , but recent science______that people who don’t sleep well soon get ill.

Years ago we didn’t know this, but recent science _______ that people who don’t sleep well soon get ill.

   A. showed        B. has shown       C. will show       D. is showing

 Years ago we didn't know this, but recent science ______ that people who don't sleep well soon get ill.

A. showed              B. has shown        C. will show         D. is showing

 Years ago we didn't know this, but recent science ________ that people who don't sleep well soon get ill.

A. showed            B. has shown            C. will show            D. is showing

Years ago we didn't know this, but recent science ________ that people who don't sleep well soon get ill．

1. A.
   showed
2. B.
   has shown
3. C.
   will show
4. D.
   is showing

Years ago we didn't know this, but recent science ________ that people who don't sleep well soon get ill.

1. A.
   showed
2. B.
   will show
3. C.
   has shown
4. D.
   is showing