So far, several cases of a disease, ________ as H1N1, 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 H1N1, 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 H1N1, 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 H1N1, 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 H1N1, are reported to have been found in the country.