根据句子意思，用括号中所给汉语提示或英语单词的适当形式填空。（每空一词）
 Food          has been a serious problem in China in recent years such as fake milk　powder（劣质奶粉）, Toxic Capsules（问题胶囊）. (safe)
 These comic books ________ (it) are more or less worth reading.
——Is London the first European city        the Olympic Games?——No, it has been held in many other places in Europe.  (hold)
 More than one person ________(clean) the classroom at 6 o'clock yesterday.
 It's said that the price of food in China _____ ( rise ) quickly recently.
 The fish is_____ ( terrible) bad, why not throw it away?
 The famous writer always spends as much time as he can       to his fans' e-mails. (reply)
 The suspect ___________(see) running along the street at that time.
 _______ ( take ) more exercise and you'll become healthier.
 Though the hike is far ___________ ( tough), I'll try to finish it.