问题补充：
He is a man of few words, and seldom speaks until to.
A. spoken
B. speaking
C. speak
D. be spoken
答案：
(答案→)A. spoken
B. speaking
C. speak
D. be spoken
解析：此题容易误选B，认为until是介词，后接动词时用动名词形式。其实，此题应选A，until spoken to为until he is spoken to之省略。句意为“他是个沉默寡言的人，别人不同他说话，他很少同别人说话”。按英语习惯，一些表示时间、地点、条件、方式、让步等的状语从句，若其主语与主句主语一致，且从句谓语包含动词be,那么可将从句的主语和动词be省略：
You must study hard while (you are) young, or you will regret when (you are) old.趁年轻时要努力学习，不然到老了你会后悔的。
I won go unless (I am) invited.我不会去,除非请我。
Look out for cars when (you are) crossing the streets.过马路时要注意汽车。
While (I was) waiting I was reading some old magazines.等的时候我在看一些旧杂志。
He worked very hard though (he was) still rather poor in health.尽管身体还不好，但他仍努力工作。
He will work hard wherever (he is) sent by the Party.无论党把他派往哪里,他都会努力工作。
