Weworked for several hours and we were happy to see that the forest looked cleanerthan it had looked before.
请问这里 than 后面的主语 it 可以省略吗？
譬如像下面如此的句子：
The results are less satisfactory than had been anticipated. 结果没着预期的那样让人认可。
Therewere many more deaths than was first supposed. 死亡的人数要比刚开始预想的多得多。
We worked for several hours and we were happy to see that the forestlooked cleaner than it had looked before.
句中 than 后面的主语 it 不能省略——关于这个问题，本站已有不少讨论，你可以参考关键字搜索一下，认真去看看。特别是剑桥语法提到的看法，值得注意。
关于 than 比较分句省略主语，主要限于以下两种状况：
一是than分句的主语是主句比较项的对应成分（此时习惯上需要省略）。如：
More trees werecut than were planted. 砍伐的树比种植的树要多。（比较分句省略的主语与主句中的比较项 more trees相对应，所以需要省略）
More food iswasted than is eaten in this canteen. 在这个饭店里浪费的食品比吃掉的还多。（比较分句省略的主语与主句中的比较项 more food 相对应，所以需要省略）
More people diedof flu in 1919 than were killed in the First World War. 1919年死于流感的人比首次世界大战死的人还多。（比较分句省略的主语与主句中的比较项 more people相对应，所以需要省略）
二是than分句用了形式主语而将真实主语外置，此时既可省略形式主语和外置主语，也可以不省略（同时省略或同时保留）。如：
The situation waseven worse than was supposed. 状况比料想的还糟。（=…than it was supposed that the situation should be.）
Never give himmore money than is necessary. 不要给他超出需用的钱。（=…than it is necessary that you should give him.）
More middle-agedpersons suffer from hypertension than is generally realized. 患髙血压症的中年人比一般获悉的要多。（=…than it is generallyrealized that they would suffer.）
下面剖析一下你的句子：
The results areless satisfactory than had been anticipated. 结果没着预期的那样让人认可。（比较分句省略的主语与主句中的比较项less satisfactory相对应，所以需要省略）
There were many more deaths than was first supposed. 死亡的人数要比刚开始预想的多得多。（=…than it was first supposed that there should have been.）
