Tom: William has asked me for a loan of five pounds. Should
　　 I be doing right in lending it to him?
Jack: Certainly.
Tom: And why?
Jack: Because otherwise he would try to borrow it from me.

汤姆：威廉向我借五英镑。我该不该借给他？
　　　杰克：当然应该了。
　　　汤姆：为什么？
　　　杰克：否则他就该跟我借了。

否则