Are the following sentences meaningful to a native speaker?
1.I have to be creative.It helps me to compete with rivals and be one step ahead of them ( or to be one step ahead of them ).
2.It Improves students' creativity, and they will end up with higher grades.
3.Air pollution is an urgent concern and the reason lies on fossil fuels.
4.Students can study together and this will benefit their teamwork skills.( Here I want to use benefit not improve.How should I?)
5. weak economy / strong economy: lack of experts leads to a weak economy
6.many students struggle with their lessons.Their weakness lies in (or lies on ?) their approach.