Find a word which does not belong in each group

1. Find a word which does not belong in each group
1. A. rock B. waterfall C. river D. lake
2. A. long B. deep C. wonderful D. high
3. A. watch B. see C. enjoy D. look
4. A. island B. mountain C. bay D. building
5. A. must B. have C. should D. can