求问一道that和in which 的题~突然想不清楚了..求抽出两分钟帮我看一下~~

mie025

In an effort to reduce the number of fires started by cigarettes, a major tobacco company is test-marketing a cigarette in which thin layers of extra paper are used to decrease the amount of oxygen entering the cigarette, thereby slowing the rate at which it burns and lowering the heat it generates.

1. in which thin layers of extra paper are used to decrease the amount of oxygen entering the cigarette, thereby slowing
   
   
2. in which they use thin layers of extra paper in decreasing the amount of oxygen entering the cigarette, which slows
   
   
3. that uses thin layers of extra paper to decrease the amount of oxygen when it enters the cigarette, thereby slowing
   
   
4. for which thin layers of extra paper are used to decrease the amount of oxygen that enters the cigarette, and thereby slowing
   
   
5. using thin layers of extra paper in decreasing the amount of oxygen entering the cigarette, which slows
   
   答案选A
   这里的in which要怎么解释
   为什么C的that不行呢
   望指导一下小白！！
   

naoyixue

首先，这里的我觉得in which比that好， 因为本身香烟没有能动力来use或者不use,只有人来use,但是A的选项，写了in which强调了这么一个结果（thiner layers are used) . 同时，可以不九届C，因为C德it后和后面的it指代不同，一个带香烟，一个带oxygen.