1. Have you seen my book? Ive been looking ___ it

1. Have you seen my book? Ive been looking for it everywhere! 2. What  a great discovery Columbus мейд! 3. There are many people walking along the bank of the river. 

In the first sentence we use for because to look for means to search something. In the second we use what and in the third sentence we use bank because shore is used with sea and coast also but the bank of the river.