Suppose/Supposing (that) ...
  結構︰Suppose/Supposing (that)+子句,S+V ...
  說明︰此句型意為“如果…,假使…”。Suppose/Supposing (that) 引導假設條件句,其功能相當於 if。
  Suppose/Supposing (that) we miss the train, what shall we do?
  如果我們誤了火車,我們將怎麼辦?

  What if/Say ...
  結構︰What if/Say+子句,S+V ...
  說明︰此句型意為“假設…”。What if 和 Say 用來引導一個假設條件句,其義相當於 Let us suppose(讓我們假設)。
  What if/Say he goes home before us and can’t get in? What will he do then?
  假設他在我們之前趕到家而又進不去呢?那他怎麼辦呢?
  What if/Say you were to run out of money? What would you do?
  假設你的錢用完了呢?你將怎麼辦呢?

  With luck ...
  結構︰With luck,+主要子句
  說明︰With luck 為含蓄假設條件句(即不用 if 直接引導)。with luck 意為“如果幸