______him do this job by himself?

A) Why don't let      B) Why not let      C) Why not letting    D) Why you not let

______ made him unhappiest of all was ______ he had nowhere to unburden himself.

______ made him unhappiest of all was ______ he had nowhere to unburden himself.

A．What; what        B．What; that         C．That; what         D．That; because

Leave him alone.He is ________ himself to the preparations for the coming exam.

A．adjusting  B．applying

C．losing  D．engaging

He himself can't finish so much work in such a short time ________ he workshard day and night or others help him．

1. A.
   while
2. B.
   until
3. C.
   unless
4. D.
   though