— No one can answer the question _______ we can complete the task in time, do you know?

— Yes, and this is because we don’t know the way _______ the scientist used last time．

--- No one can answer the question ______ we can complete the task in time, do you know?
--- Yes, and this is because we don’t know the way ______ the scientist used last time．

1. A.
   whether; which
2. B.
   if; which
3. C.
   whether; in which
4. D.
   if; in which

— No one can answer the question _______ we can complete the task in time, do you know?

       — Yes, and this is because we don’t know the way _______ the scientist used last time．

       A．whether; which               B．if; which      

       C．whether; in which        D．if; in which

— No one can answer the question _______ we can complete the task in time, do you know?

— Yes, and this is because we don’t know the way _______ the scientist used last time．

A．whether; which                             B．if; which

C．whether; in which                             D．if; in which

— No one can answer the question _______ we can complete the task in time, do you know?

— Yes, and this is because we don’t know the way _______ the scientist used last time.

A. whether; which        B. if; which          C. whether; in which    D. if; in which