`1,` The problem can't be solved by us.
`2,` Experiments on animals should be stopped.
`3,` Life on another planet might be found.
`4,` All the schools in the city have to be improved.
`5,` A new bridge is going to be built in the area.
`6,` Jeans were worn by many university and college students.
`7,` Different styles of jeans were made to match the 1960s’ fashions by designers.