2级
单选题The word“they”underlined in Paragraph 4 refers to________．
参考答案：B进入在线模考
词义题型
见第四段第一句：By April l978，WHO officials announced that they had solated the last known case of the disease．根据句子结构判断，they指的是前面提到的WHO officials，因 此B为答案。
见第四段第一句：By April l978，WHO officials announced that they had solated the last known case of the disease．根据句子结构判断，they指的是前面提到的WHO officials，因 此B为答案。
