曼哈顿 句子改错疑惑

请教各位大佬，曼哈顿第二章，以下这两句并不明白为何正确，也不明白意思，求帮助！

1. Hector remembers San Francisco as it was when he left 10 years ago.

1. The boldface version changes to the original version, but the new version could make sense.

The original sentence says that Hector actually DID leave San Francisco 10 years ago. The revised version says that he did NOT leave San Francisco 10 years ago: the expression as though is used to discuss things that are untrue or did not happen (You behave as though you were richer than Bill Gates!).

Another important change in meaning comes because the revised version takes out the words it (i.e., San Francisco) was, and therefore does not refer directly to the state of affairs in San Francisco 10 years ago.