已知函数$f\left(x\right)={\log }_{\frac{1}{2}}(x^2-ax+4a)$在$2,+\infty )$单调递减，则a的取值范围（    ）

增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：1）每处错误及其修改均限一词；

2）只允许修改10处，多者（从第11处起）不计分。

    I lost my passport two days before at about 8:30 in the evening that I bought three dictionaries at the MBC bookstore. By accidents, I left my passport at the shop. When I realized what I have done, I telephoned the shop, but the shop assistants there could not find one. I would be grateful if you could tell me what documents I need send you in order to get a new passport. Do you require any passport photographs, and if so how many? How much will a new passport cost but in which currency would you like me to pay off? I must apologize to any inconvenience caused and look forward to hear from you soon.

根据句意及首字母提示完成句子