问题
选择题
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
答案
答案：D
考查非谓语。know 与cases为动宾关系所以用过去分词作定语。到目前为止据知是禽流感的几个病例在这个国家被发现并报道。