1.have been attracted
2.was discovered
3.turned
4.to be
5.built
6.called
7.is
8.produces 
9.discovered
10.was built
11.see
12.arriving
13.is
14.are always made 
15.search
16.have to
17.spend
18.find
19.is
20.is called
21.dug
22.live
23.built