難點(diǎn)釋疑：

　　1.當(dāng)hardly, scarcely, no sooner位于引起的句子的開頭時(shí)，常用倒裝語(yǔ)序。

　　No sooner had he arrived there than he fell ill.

　　Hardly had he finished when someone rose to refute his points.

　　Scarcely had she fallen asleep when a knock at the door awakened her. 這三組關(guān)聯(lián)詞引起的句子中，前面常用過去完成時(shí)，后面用一般過去時(shí)。

　　2.if和unless的用法

　　一般情況下，unless相當(dāng)于if…not，可以互換。如：

　　I won't let you in unless you show me your pass = I won't let you in if you don't show me your pass. 如果你不出示通行證，我就不讓你進(jìn)來。