Reaserchers are studying  plastics that disslove at different rates, and they are finding that so-called 'quick disintegration' plastics are taking more time to deteriorite than【 they originally seemed】.
1.they originally seemed
2.they seemed originally
3.it seemed that they would originally
4.it originally seemed
5.it originally seemed they would


OA 是5  我选的是1     那位大牛可以帮忙解释一下答案啊 万分感谢

第二句中第一个THEY是指代RESEARCHERS，所以选项1和2的THEY根据代词指代一致原则也得指代研究者，而逻辑意思上THEY指导PLASTICS。所以1，2不可选.

这是一个指代题目加比较
首先是they 和it ,选那个，就像楼上说的那样。其实我也挺含糊的~
C语法错误，副词修饰的是情态动词？说不过去
D我本来觉得挺正确，但是看了E以后，觉得~than前面是一句完整的话，than后面有 主语it 谓语seemed (修饰副词忽略)，肯定需要把句子说完整。
话说GMAT中，简洁和句子的完整性常常模棱两可。。。
说的可能不清楚，还等高人指点。

那个THEY 和 IT 真的挺难区分的，有没有人再来讲讲~

但我还是不明白5中seemed后面为什么不用加that?  请高人指点。

首先originally在原句中修饰seemed，地方不能变化，所以排除2，3。其次最重要的这里是taking more time to deteriorite这个动作做比较，为了平行than后面必须接动作，光用they不能和前面的动作比较。1，4后面需要加上to （do）。5后面是would （do）, do被省略了的用法。不过seemed后面的表语从句that居然能省略，比较奇怪。

如果硬是要解释D，把D写完整，那就是
....than it originally seemed (that) they would find (that so-called 'quick disintegration' plastics are taking  to deteriorite )
they还是指RESERCHERS。前面是they are finding,相应的后头是they would find.find可用DO代替.DO前面有个WOULD,所以DO又可省去
后面部分跟前头一样，删掉。