Question

(   ) 4.  When H7N9 bird flu first appeared,people didn’t know        doctors could cure it.

   A. if   B. that

   C. what   D. why

Answer 1

4. A根據句意“當H7N9流感首次出現的時候，人們不知道醫生是否能夠治愈它”可推知此空應表示 “是否”，只有A項符合。