根据句子意思，用括号中所给单词的正确形式填空。(每空限填一个单词)
【小题1】Art has real _____________ (mean) when it helps people to understand life.
【小题2】I knew that Tim and I wouldn't be able to do the whole job by_______________  (us),
【小题3】Parents often feel _________ (help), knowing that all the efforts won't improve their child's study.
【小题4】This last math exercise is ____________ (possible) the most difficult one that I have ever met.
【小题5】"We've come with good news," Pat said _______________  (cheer).