________ what to say, he kept silent.

1. A.
   No knowing
2. B.
   Knowing not
3. C.
   Not knowing
4. D.
   Knowing no

________ what to say, he kept silent.

[　　]

________ what to say, I kept silent.

[　　]

________ what to say, I kept silent.

[　　]

________ what to say, he kept silent.

[　　]