“進行時+when+一般時”表示“正在……，就在這時”
   孩子們正要離開學校，這時他們看見了一輛卡車。
   【誤】The children left school when they saw a truck.
   【正】The children were leaving school when they saw a truck.
   2．while不能用于含有表示一時性動作的動詞的句子
   當我講話的時候請安靜。
   【誤】Please be quiet while I speak.
   【正】Please be quiet while I am speaking.

   3．表示一時性動作的動詞，如：finish, return, start, leave, come, reach, go要用其否定式與till/until連用
   我恐怕要在他來之前才能完成工作。
   【誤】I‘m afraid I can finish the work when he comes.
   【正】I‘m afraid I can‘t finish the work until/till he comes.
   表持續性動作的動詞，如：stay, wait要用其肯定形式與till/until連用。
   我呆在那里直到他回來。
   【誤】I stayed there when he arrived.
   【正】I stayed there until/till he arrived.

   4．because所引導的從句可放在句首；for連接的分句不能放在句首
   他不害怕，因為他很勇敢。
   【誤】For he was very brave, he felt no fear.
   【正】He felt no fear, for he was very brave.
   because表示直接的原因；for表示推斷的原因。
   一定是早晨了，鳥在叫呢。
   【誤】It must be morning now, because the birds are singing.
   【正】It must be morning now, for the birds are singing.
   分析：早晨到來的直接原因是太陽升起，而決非是鳥唱歌。鳥唱歌只表示推斷的原因。

   5．不能把because或so用在同一個句子中來表述中文的“因為……所以……”
   他因粗心而失敗。
   【誤】Because he was careless, so he failed.
   【正】He failed because he was careless.
   【正】He was careless, so he failed.

   6．although引導讓步狀語從句，主句不再用任何連詞。不能把although和but用在同一個句子中來表述中文的“雖然……但是……”
   雖然他很累，但他仍繼續向前走。
   【誤】Although he was tired, but he still went on.
   【正】Although he was tired, he still went on.
   【正】He was tired, but he still went on.

   7．在否定句中，表示并列關系時連詞不用and，而用or
   我從沒去過上海和南京。
   【誤】I have never been to Shanghai and Nanjing.
   【正】I have never been to Shanghai or Nanjing.