托福阅读长难句精讲：whether和if的用法区别

## 托福阅读长难句 One of the most difficult aspects of deciding whether current climatic events reveal evidence of the impact of human activities is that it is hard to get a measure of what constitutes the natural variability of the climate. ## 专家解析 ### 【子句拆分】 主句：One of the most difficult aspects of deciding something is something. 宾语从句1：Current climatic events reveal evidence of the impact of human activities. 表语从句：It is hard to get a measure of something. 宾语从句2：Something constitutes the natural variability of the climate. ### 【成分划分】 主句：One of the most difficult [定语] aspects [主语] of deciding something [定语] is [系动词] something. [表语] 翻译：确定某事最困难的方面之一是某事。 连接词：whether 宾语从句1：Current climatic events [主语] reveal [谓语] evidence [宾语] of the impact of human activities. [定语] 翻译：当前的气候现象证明了人类活动的影响。 连接词：that 表语从句：It [形式主语] is [系动词] hard [表语] to get a measure of something. [主语] 翻译：很难找到一个标准来评估某事。 连接词：what 宾语从句2：Something [主语] constitutes [谓语] the natural variability [宾语] of the climate. [定语] 翻译：某事是自然的气候变化的因素。 ### 【全句翻译】 当前的气候现象是否证明了人类活动对其产生的影响？确定这一点最困难的方面之一就是，很难找到一个标准来评估那些导致自然的气候变化的因素。 ## 知识点梳理 ### whether和if的用法区别 whether和if都可以引导宾语从句，表示“是否”，在口语或间接引语中两者可以互换使用。 如：I wonder if / whether I can get some advice from you. Ask him whether / if he can come. 但在有些情况下，whether和if的用法有一定区别。 1. whether引导的从句常可以与连词or或or not直接连用，而if一般不能。如： 例句1：Let me know whether you can come or not. 2. 当宾语从句提到句首时，只能用whether引导，而不能用if。如： 例句2：Whether it is true or not, I can’t tell. 3. whether可以引导带to的不定式，if则不能。如： 例句3：I don’t know whether to accept or refuse. 4. whether及其引导的成分可放于介词之后，作介词的宾语，但if不能。如： 例句4：I worry about whether I hurt her feelings. 5. whether可以引导从句，作主语、表语或同位语，而if不能。如： 例句5：It was uncertain whether he would come. 例句6：His first question was whether Tom had arrived yet. 例句7：We must consider the question whether we will take these measures.