_____ a certain doubt among the workers as to whether he could finish the task in a short time．

_____ a certain doubt among the workers as to whether he could finish the task in a short time．

1. A.
   It was
2. B.
   There had
3. C.
   There existed
4. D.
   It had

_____ a certain doubt among the workers as to whether he could finish the task in a short time．

A．It was                     B．There had               C．There existed           D．It had

_____ a certain doubt among the workers as to whether he could finish the task in a short time．