【真題例句】Since our chief business with them is to enable them to share in a common life we cannot help considering whether or not we are forming the powers which will secure this ability。(2009-49)

　　【結構分析】本句句首部分即為Since引導的原因狀語從句，since our chief business with them is to…，其中表語部分由不定式短語充當。主句部分為we cannot help considering…，consider的賓語部分由whether or not引導的名詞性從句充當，其中又包含一個which引導的限制性定語從句which will secure this ability修飾先行詞powers。

　　【參考譯文】既然我們的主要任務在于使年輕人參與共同生活，我們禁不住考慮我們是否在形成獲得這種能力的力量。

　　注意：for作為連詞，后面的句子為并列分句，不是從句。在其前面經常出現逗號，對上文的情況加以解釋(參見并列平行結構章節)。

　　(五)條件狀語從句

　　該類從句連接詞主要有 if, unless, as/so long as, on condition that 等。

　　1.if引導真實條件句

　　【真題例句】And if one received a grape without having to provide her token in exchange at all, the other either tossed her own token at the researcher or out of the chamber, or refused to accept the slice of cucumber。(2005閱讀1)

　　【結構分析】此句為復合句。逗號前為if引導的條件狀語從句，主句中第二個or并列兩個謂語refused to accept 和 tossed 構成的主干the other either tossed her own token, or refused to accept the slice of cucumber。

　　【參考譯文】如果一只猴子完全不需要用她的代幣交換就可以得到葡萄的話，那么另一只猴子就會將代幣扔向研究人員或扔出房間外，或者拒絕接受黃瓜片。

　　2.if引導非真實條件句

　　【真題例句】If it did, it would open up its diversity program, now focused narrowly on race and gender, and look for reporters who differ broadly by outlook, values, education, and class。(2001閱讀3)

　　【結構分析】if引導非真實條件句，從句采用if+did，與現在相反，主句為would do形式。其中now focused narrowly on race and gender我們可以理解為分詞后置作定語，全句主干部分為it would open up its diversity program…and look for reporters…，其中reporters后又跟who引導的定語從句，修飾先行詞reporter，關系代詞who在從句中作主語。

　　【參考譯文】假如新聞界注意到了這一問題(參見前文)，就應該開辦多樣化項目——現在項目狹隘地局限于種族和性別，并且尋找世界觀、價值觀、教育程度和社會階層大不相同的各類記者。

　　【真題例句】If railroads charged all customers the same average rate, they argue, shippers who have the option of switching to trucks or other forms of transportation would do so, leaving remaining customers to shoulder the cost of keeping up the line。(2003閱讀3)

　　【結構分析】if引導非真實條件句，從句采用if+did，與現在相反，主句為would do形式。they argue為插入語，分隔了從句與主句。主句中，主語shippers后又who引導的定語從句，關系代詞who在從句中作主語。句子末尾leaving remaining customers to shoulder the cost of keeping up the line為分詞結構所作的伴隨狀語。

　　【參考譯文】他們辯稱，如果鐵路公司向所有客戶收取同樣的均價，一些即可以選擇通過卡車又可以選擇其他運輸方式的人就會選擇卡車或其他的運輸方式運貨，而由剩余的客戶來承擔鐵路正常運作的開銷。

　　【真題例句】In dealing with a challenge on such a scale, it is no exaggeration to say “United we stand, divided we fall”—and if I had to choose a slogan it would be “Unity in our diversity”。(2005-50)

　　【結構分析】句首部分為介賓所作的狀語，主句為it作形式主語，不定式作真正主語的it is no exaggeration to say “United we stand, divided we fall”。破折號后if引導非真實條件句，從句采用if+did，與現在相反，主句為would do形式，對前部分補充說明。