1. I am appreciated to the co-worker who is willing to help at work.
-> A co-worker / who is willing to help out at work / is appreciated.
2. Instant foods which contain lots of preservatives are unhealthy.
-> Instant food, which contains many preservatives, is unhealthy for the body.
3. I would like to work for a company at the job, which I can be promoted quickly.
-> ~ where I can advance quickly.
4. Sometimes, memories that last for a lifetime are valuable than jewelry.
-> Sometimes memories, which can last for a lifetime, are more valuable than jewely.
5. Children who start their education to be educated at an early age have difficulty making friends.
6. These are several reasons why it is better for saving the money for future.
-> These are some of the reasons why it is better to save your money for the future.
7. I like having friends whom have many things in common with.
-> I like having friends who I have a lot in common with.
8. We are living in society that the amount of money they make determines the success.
-> We live in a society / where people determine success by the amount of money the make.
9. People often feel that there are no other people they understand.
-> People often feel that there is no one that understands them.
10. The items which made by hand often have the highest quality.
-> Items that are made by hand often have the highest quality.
11. Parents who push their children may cause them to rebel.
-> Parents that push their children too hard may cause them to rebel.
12. It is hard to find good employees that why I hire experienced people at a high salary.
-> Good employees are hard to find, which is why I would hire an experience worker at a higher salary.
13. It is easier to learn a language when you are young.
14. One of the best friends is someone who makes you smile.
-> The best kind of friend is someone who can make you laugh.
15. I will never be a type of parents who push their children seriously.
-> I'd never want to be the type of parent that pushes his children too hard.