We need therefore to know how much the climate can vary of its own accord in order to interpret with confidence the extent to which recent changes are natural as opposed to being the result of human activities.
主句：We need therefore to know something in order to interpret with confidence the extent.
定语从句：To some extent recent changes are natural as opposed to being the result of human activities.
宾语从句：The climate can vary of its own accord.
主句：We [主语] need therefore to know [谓语] something [宾语] in order to interpret with confidence the extent. [状语]
定语从句：To some extent [状语] recent changes [主语] are [系动词] natural [表语] as opposed to being the result of human activities. [状语]
宾语从句：The climate [主语] can vary [谓语] of its own accord [状语] in order to interpret with confidence the extent. [状语]
例句1：The girl **with whom** you **work** is his girl friend.
例句2：The goals **for which** he had **fought** all his life no longer seemed important to him.
例句3：He referred me to some reference books **with which** I am not very **familiar**.
例句4：They will pass along their fresh impressions to the youth groups **in which** they are **active**.
例句5：I am sending you an inquiry, **to which** your prompt **attention** is highly appreciated.
例句6：About a thousand species of animals are in danger of extinction, and **the rate at which** they are being destroyed has increased.
要想正确地使用介词，我们必须记住相关的介词短语搭配。常见的有：with ease，at the
rate，in the direction，to the extent，to the degree，at the temperature，by the means，by the mode，in a culture，in practice 等等。