选项A：the crystal dissolves，晶体溶解是 infect the insect's cells的条件

老师，关于AE选项
while和but没有区别吗？
it可有可无吗？

if protected from direct sunlight, they may remain virulent for many years in the environment, embedded in durable crystals of polyhedrin protein.

underway adj.进行中的，已经开始的。选项D是对原文句子的直接改写

For many years, viral disease had been reported in declining populations of caterpillars, but population ecologists had usually considered viral disease to have contributed to the decline once it was underway rather than to have initiated it.

考点：名词、不定式、动名词、从句分别作宾语的区别

因为研究者发现：1）测量由鸟类等捕食者造成的死亡率 ； 2）通过改变habitats，或者减少了毛毛虫的数量的办法 change life cycle； 两者都没有成功
conclusion:这些虫子如果不是自我调节，就是由一个和昆虫有紧密关系的东西所调节的
C选项说病毒存在于病毒存在于一些捕食者的体内，加强了病毒和昆虫的联系

P2是对P1提出的理论在实际中的指导应用

BD考点
B选项，with独立主格作状语（修饰主句） 与 with介词短语作定语（修饰shuttle and spacecraft)，模棱两可
D选项，定语从句直截了当修饰前面名词，能有效避免歧义

定位：A manufacturer's fixed costs and "sunk costs" (original capital investment in the physical plant) do not decrease when production declines due to inadequate supplies of raw materials, problems on the factory floor, or inefficient sales networks.
固定成本和沉默成本并不会在生产下降的时候减少

定位Such industries are quickly dominated, not by the first firms to acquire technologically sophisticated plants of theoretically optimal size, but rather by the first to exploit the full potential of such plants.

However, whereas cactus-flower abundance tends to be high during spring, bat population densities tend to be low except near maternity roosts.
花的数量很多，但是相对bats的密度偏低。->导致了bats无法给所有的花授粉

现象说明型文章：
P1描述了沙漠里的柱状仙人掌等植物的花原本只在夜间进行授粉，后来逐渐进化出了在白天也能被授粉的功能。
P2解释这种进化可能因为bats在一年中数量的变化；以及bats数量的变化有3个可能的原因。
P3解释了bats数量变化是3个原因中的1个情况

三种易混“宾补“
1、不定式
2、v-ing分词
3、从句

定位： A virtuous citizenry was considered essential to the success of the country’s republican form of government; virtue was to be instilled not only by churches and schools, but by families, where the mother’s role was crucial.

LK认为 American Revolution 推动了女性受教育权利；TW认为在此之前女性受教育机会已经增加了。

定位：Pointing to “An Essay on Woman” (1753) as reflecting a shift in view, Woody also claimed that practical education for females had many advocates before the Revolution.
TW认为"AN Essay on Woman"反映了观念上的转折点

定位：Prior to Kerber’s work, educational historians barely mentioned women and girls; Thomas Woody’s 1929 work is the notable exception.
选项B：关注了AR之前的时期。从逻来说并非是因为TW关注了AR之前的时期才导致他的研究exceptional。而是因为TW检验了女性和女孩的教育，发现了在AR之前女性教育机会已经增加了（TW的conclusion）

第5句，是不是也可以理解为from xx to xx是一个状语，如何switch？

instead/instead of
instead, 副词，表转折、代替，通常用于句尾
It will take days by car, so let’s fly instead.
instead of作介词，后面跟名词、动名词，如I will go instead of you.；Instead of doing it himself, he got a man to do it.
Instead of也可以做连词，后面还可跟形容词、副词、动词、不定式、介词短语和从句
makes him look younger instead of older
That increased instead of decreased our courage.
He proposes to do some work instead of to watch television.