在But not before Mr. Budd had seen the misshapen thumbnail.中，我们先看Mr. Budd had seen the misshapen thumbnail（大意是Mr. Budd已经看到了他的拇指的指甲是残缺的。）注意这句用的是过去完成时，说明看见的动作已经发生了。在看But not，在前文找saw him suddenly pull back his left hand, which had been resting carelessly on the arm of the chair.（看见他突然把他的手缩了回去，然而那手随意放在椅子扶手上），有趣的是作家用which引导一个定语从句，描写那个手，凸显，放大了那个手实实在在呈现在Mr. Budd眼前，Mr. Budd看到了，但是那位The stranger 没有来得及快速缩回去，所以，这里的but表达了可是，not浓缩了前文的pull back his left hand的信息内涵：没有来得及把手藏起来，就被Mr. Budd发现了。But not 神来之笔。

    注意这里的before,它的位置虽然放在Mr. Budd had seen the misshapen thumbnail.前的，实际上和前面的But not构成一个意群。如：

   新概念英语第二册有一句：I had nearly reached the town， when the young man suddenly said中the young man suddenly sai的动作发生在I had nearly reached the town，when在这里指的是I had nearly reached the town，在第14课练习中有一个针对这句话的回答练习：

    When did the young man suddenly said,"Do you speak English？显然这里的when指的是I had nearly reached the town，

同样before指的是but not，合起来就是：可是没得及把手藏起来之前，Mr. Budd已经看到了他的拇指的指甲是残缺