Question

Our English teacher worked late into the night, ______ the exams for the follow weeks.

1. A.
   to be prepared
2. B.
   prepared
3. C.
   preparing
4. D.
   was preparing

Answer 1

C
该题考查现在分词短语做状语。Preparing不是并列谓语动词，而是伴随状语，用来对谓语的动作加以修饰或陪衬；过去分作伴随装语，用来说明动作发生的背景或情况，如Depressed he went to see his sister（他情绪低落就跑去找他的姐姐）。