【受動態の解答】 
１．
　⑴ The  children  are  liked  by  her. 
　⑵ Some  sandwiches  were  bought  by  Mother  yesterday.  ＊　Mother, Father が単独で使われる場合は固有名詞扱い 
　⑶ This  dictionary  will  be  used  by  Sam.  
　⑷ These  books  aren't  read  by  her.  
　⑸ Were  any  stamps  collected  by  him? 
　⑹ He  was  given  a  watch  by  her. 
　   A  watch  was  given （to） him  by  her. 
　⑺ She  is  called  Mika （by  us）.　　　＊　We  call  her  Mika.（彼女はミカと呼ばれている）
　                               　　　　　　　　S   V     O     C 
　⑻ The  work  must  be  done  by  him. 
　⑼ I  was  spoken  to  by  an  old  man  in  the  bus.  ＊　speak  to 「話しかける」　⇒　be  spoken  to 
　⑽ I  was  sometimes  taken  to  the  park  by  my  father. ＊　sometimes  はbe動詞の後ろ。
　⑾ A  lot  of  butterflies  can  be  found （by  us）in  the  forest.
　⑿ When  was  the  house  sold  by  him?  
　⒀ What  was  sent  to  her  by  Ken? 
　⒁ Where  was  this  box  made  by  her? 

２．
　⑴ with  富士山の頂上はいつも雪でおおわれています。 ＊　be  covered  with ～「～におおわれている」 
　⑵ at    私たちは彼の話に驚いた。 ＊　be  surprised  at ～「～に驚く」 
　⑶ to    彼女の名前はみんなに知られている。 ＊　be  known  to ～「～に知られている」 
　⑷ in    あなたはどんな本に興味をもっていますか。 ＊　be  interested  in ～「～に興味をもっている」 
　⑸ of    これらの家は木で作られていますか。 ＊　be  made  of ～「～で作られている」 
　⑹ with  彼女はそのかばんが気に入りました。 ＊　be  pleased  with ～「～が気に入る」 

３．
　⑴ They  speak  Chinese  in  Singapore. 
　⑵ We  can  catch  a  lot  of  fish  in  the  river. 
　⑶ We  could  see  stars  last  night. 
　⑷ What  did  Mary  use? 
　    ＊　受動態の文に行為者（ by ～）が示されていない場合は、 能動態に直す時に主語を表さなくてはならない 
　
４．
　⑴ I  was  born  in  Japan  in  1960. 
　⑵ Some  cakes  are  sometimes  made  by  Yoshiko. 
　⑶ Are  you  pleased  with  the  bag? 
　⑷ The  room  is  usually  cleaned  by  Mother.   
　    ＊　sometimesやusually  はbe動詞の後ろ。