It is only when the disease has progressed to the AIDS ____ a person begins to look sick. A．..

It is only when the disease has progressed to the AIDS ____ a person begins to look sick. A．..

D

试题分析：句意：只有当疾病发展成艾滋病时，一个人看起来才像是病人。这里是强调句型，其结构是It was+被强调部分+ that+其他，判断强调句型的方法是把It was that去掉整个句子不缺成分，是成立的。这里强调的是时间状语从句，故用that。 点评：本题难度适中。强调句型是高中阶段的重难点之一，也是高考的热点，需要考生有分析理解句子的结构的能力。近几年高考把强调句型与其他从句混合在一起考查更增加了试题的难度。 即学即练：It was not until midnight____they reached the camp site. A. that    B.when   C.while   D. as 解析：A。句意：该题强干扰项是B，考生容易因强调时间状语until midnight而误选。