The area from the coastline to about halfway up the hillside was covered by the web that was too thick to see through.

from the coastline 是介词+名词，而to about halfway up the hillside中to是介词，about halfway是副词词组，修饰up the hillside这个介词词组。不知道上述分析对否？这样一来,from...to...这个结构中from后跟的是名词(the coastline)，而to后跟的不是名词，是经过副词词组(about halfway)修饰的介词词组(up the hillside),这样是否可行，是否恰当？

【答】你的分析对错参半。

1. 这句话的主干是：（见红色部分，其余都是定语修饰语）

The area from the coastline to about halfway up the hillside was covered by the web that was too thick to see through.

2. from the coastline to about halfway up the hillside：这是from...to...介词短语，表示范围，作定语修饰the area。

3. from...to...，在两个介词后面的介词宾语，应该都是名词性的词语。所以，from的宾语是the coastline；to 的宾语是about halfway（大约半山腰的位置，halfway 是副词，在此是名词用法），介词短语up the hillside 是halfway 的定语。

4. that was too thick to see through：是定语从句修饰the web。

【翻译】从海岸线到半山腰的那片区域被网络覆盖着，网络太密集看不清楚。