獨(dú)立主格結(jié)構(gòu)主要表示謂語動(dòng)詞發(fā)生的時(shí)間、原因、條件或伴隨情況等，相
當(dāng)于一個(gè)狀語從句或并列句。

    1.用作時(shí)間狀語The work done （=After the work had been done ）， we
went home.工作完成后，我們就回家了。2.用作條件狀語Weather permitting
（=If weather permits ）， they will go on an outing to the beach tomorrow.
如果天氣允許的話，他們將在明天組織一次海濱小游。3.用作原因狀語An important
lecture to be given tomorrow（=As an important lecture will be given tomorrow），
the professor has to stay up late into the night. 因?yàn)槊魈煲�發(fā)表一個(gè)重
要的演講，教授不得不熬夜到很晚。4.用作伴隨狀語He was lying on the grass
，his hands crossed under his head （=and his hands were crossed under
his head）。他躺在草地上，兩手交叉枕在腦后。

    表示補(bǔ)充說明一個(gè)獵人走了進(jìn)來，他的臉凍得通紅We redoubled our efforts，
each man working like two.我們加倍努力，一個(gè)人干兩個(gè)人的活。注：獨(dú)立主
格結(jié)構(gòu)表示時(shí)間、條件或原因時(shí)，相當(dāng)于一個(gè)狀語從句，一般放在句首，表示原
因時(shí)還可放在句末；表伴隨狀況或補(bǔ)充說明時(shí)，相當(dāng)于一個(gè)并列句，通常放于句
末。