A dependent clause contains a subject and a predicate，but it does not express a complete thought and cannot stand alone as a sentence．Such a clause usually begins with although，because，that，when，if，or a similar word that makes the meaning of the clause dependent upon some part of an independent clause in a complete sentence．

从属分句（或从句）也包含一个主谓结构，但是不能表达一个完整的思想，它必须附属于其他结构（如一个主句）而不能单独成为一个句子。这些以从属连词although，because，that，when，if等开头的分句从属于另一个分句（主句），并在句中担当主语、宾语、状语等功能。

．．．although the machine is new．．．

．．．because our costs have risen．．．

．．．when you are ready to leave．．．

．．．that you will be promoted within the near future．

Look again at the above sentences，in which those not underlined parts are dependent clauses．

As illustrated below，a dependent clause makes sense only when it is used with an independent clause．

只有在与主句连用时，从句才有意义。

Although the machine is new，we have had a few problems with it．

Mrs．Richardson wants you to call her when you are ready to leave．