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1. Leonard: Sheldon, just let it go. Sheldon，別糾結了，讓它過去吧！

Sheldon：if I could, I would, but I can’t, so I shan’t. 如果我可以的話，我會的，但是我不可以，所以我不會。

解析：

If：如果；是否；假如；要是

（1）表示條件：主句將來時，if從句用現(xiàn)在時表示將來

例：I will arrive on time if you invite me to the party tomorrow.

如果明天的聚會你邀請我的話，我將準時到達。

What is to become lf me if you go away?

如果你要走的話，我的結果會是怎么樣？（這里to become不定式表示將來）

（2）表示是否

例：I wonder if you agree with my opinion.

不知你是否同意我的觀點

（3）表示虛擬：意為假如。

a.與現(xiàn)在事實相反

主句：should（would或could）+動詞原形? 從句：一般過去時

例：if I were you, I would not talk to him now.

如果我是你，我不會現(xiàn)在去和他說話。

If there were not for the water vapor in the air, there would be no dew.

如果空氣中沒有水汽，就沒有露水。

b.與過去事實相反

主句：should（would或could）+動詞原形? 從句：過去完成時had +動詞過去分詞

例：if you had studied harder at that time, you would have entered a better university.

如果你那時候好好學習的話，你能考上更好的大學。(過去沒有好好學習)

If the second world war had not happened, the economics of USA had not been so advanced.

如果二戰(zhàn)沒有發(fā)生過，美國的經濟不會如此發(fā)達。.

c.對將來的假設

主句：should（would或could）+動詞原形 從句：were+動詞不定式或should+動詞原形

例：if you were to make up your mind, everything would not be difficult.

如果你下定決心，任何事都不會困難。

拓展1：if only與only if

If only：要是，如if only i were you ；而only if：只有……才，如only if you work hard, can you get promoted.(主句倒裝)

拓展2: shan’t, shall not的縮寫；Shall 用于第一人稱表示征求意見。

2．Sheldon：But……since that’s what it looks like, we can rule that out. 但是，因為“不是看起來的那樣”，我們可以排除那種情況。

解析：

rule：n.規(guī)則，統(tǒng)治；v.統(tǒng)治，規(guī)則

rule out：排除，排斥；不考慮；劃去

例：The Treasury Department has ruled out using a weak dollar as the main solution for the country's trade problems.

財政部已經不考慮使用疲軟美元作為解決該國貿易問題的主要辦法。

The disaster ruled her out a permanent future for the ballerina in dancing.

那場災難使這個芭蕾舞女演員永遠無法跳舞了。

Rule it out：排除可能性

例：The police man thought the most possibility of homicide, but Joe held the view that the woman died from the commit suicide and didn’t rule it out.

警察認為這個女人死于他殺，但是Joe覺得不排除自殺的可能性。

拓展：rule-out排除法

3. Sheldon: Although what I lack in leadership, apparently I more than make up for in sewing. 雖然我沒什么領導能力，不過我的鋒刃技術還不錯。

解析：

make up for：彌補，補償

例：I just want to make up for my faults before.

我只是想彌補我之前的過錯。

What she lacks in ability makes up for in circumspection.

她的細心彌補了她能力上的不足。

拓展：make up組成，構成；編造；化妝