根据句意，用括号内所给单词的适当形式填空。
小题1:The problem is so easy that I have no difficulty (explain) it to my classmates.
小题2:If you tell him the (true)，he will be angry.
小题3:You may ask your teacher for help. He will give you a few (value) suggestions.
小题4:People in the past suffered from hunger and (ill).
小题5:I invited Sally to my party, but she refused (accept) my invitation.
