这句话为什么用silent 不用 silently ?

主语补足语
如：1.动词elect,call,name,make,find,leave等后面常接名词用作主语补足语.例如：
① The dog is called Karl.
② Coal is sometimes called stored-up sunlight.
③ He was found the right man for the job.
2.动词keep,make,paint,cut,burn,beat,wash,find,consider,wipe等后面常接形容词用作主语补足语.例如：
① The door was painted white.
② The old man was found weak.
③ The classroom is always kept clean every day.
3.动词see,watch,hear,feel,listen to,look at,imagine等后面接分词用作主语补足语.例如：
① He is often heard reading English.
② The professor was seen making an experiment in the chemistry lab.
③ The glass was found broken.
④ The classroom was found crowded with people.
4.感官动词see,watch,hear,notice,feel,make等后面接带to的不定式用作主语补足语.例如：
① He was seen to come upstairs.
② Ice is known to be in a solid state.
③ The spy was ordered to be hanged.
5.介词短语用作主语补足语.例如：
① The books in the study must be kept in good order.
② He was found in good health.
③ English is considered of great importance for us.
6.as后面接名词、形容词、分词等用作主语补足语.例如：
① English is taken as a useful means for research work.
② The news is considered as true.
③ The stool is usually thought as having four legs
④ The vase is thought as broken.
7.由what引导的名词性从句用作主语补足语.例如：
The boy has been made what he is.