to such an extent相當于so much
it litters up her desk to such an extent that every time she opens it, loose bits of paper fall out in every direction.= it litters up her desk so much that every time she opens it, loose bits of paper fall out in every direction.
that之后是結(jié)果狀語從句
the air pollution is so serious to such an extent that some freeways have been put out of use
結(jié)構(gòu)上沒有問題,但是意思上好像略有點累贅（so 和to such an extent）,不過應(yīng)該沒事that后是結(jié)果狀從 那請問to such an extent 是什么成分？謝謝！插入語