-Did you remember to give Jack the book?

-Yes, I gave it to him ________ I saw him．

1. A.
   while
2. B.
   immediately
3. C.
   once
4. D.
   suddenly

— Did you remember to give Jack the book?

—Yes, I gave it to him       I saw him.

A．while           B．immediately          C．once          D．suddenly