1- I think yes/no
I think so/I don’t think so.
Point: I hope so/I don’t hope so.
2- I work here 10 years.
This is an unfinished period of time! So, we need to use “Present perfect”
I have worked here for 10 years.
I have been working here for 10 years.
I work here every day/ I am working here at the moment.