So far, several cases of a disease,        as bird flu, are reported to have been found in the country.

So far, several cases of a disease,        as bird flu, are reported to have been found in the country.

1. A.
   knowing
2. B.
   to be known
3. C.
   having known
4. D.
   known

So far, several cases of a disease,        as bird flu, are reported to have been found in the country.

A. knowing         B. to be known       C. having known        D. known

So far, several cases of a disease,        as bird flu, are reported to have been found in the country.