1.I want to keep a tight grip on the road,but I cannot,maybe I will break my car,or hit it on a tree . This whole sentence is problematice. You can't grip a road. Maybe your car could 'grip' the road.
2."Please release your grip," she said "Get away from me!"
3.I do not want to release my grip,but I have to,or I will not even get the chance to talk with her. Grammatically okay, but kind of strange. I guess you're using 'grip' symbolically.
4.The climber slipped and lost her grip,It was so lucky that she was still alive.
5.She struggled to get away from his grip,he was very angry and didn't want to relax his grip,I knew I needed to help her.
6.Try adjust your grip on the racket,practice more and you will get it. (achieve is correct; i just made it more natural/informal)
7.We need to tighten our grip on the market,but we donot have enough employees to work for us.
8.The home team took a firm grip on the game,I strove to find a way to win them.
9.I couldn't get a grip on what was going on,I just sat in the crowd and fell asleep.
10.You need to keep a good grip on reality in this job,Gor this work you need to learn how to use these applications.
11.These tyres (good - TIRES for US) give the bus better grip in slippery conditions,they are very common in the northern part of this country.
12.This grip on the golf club is very
rough,I can grip it very well.
13.I am slowly coming to grips with these two languages,I am always appreciated by others. Good - but the second sentece doesn't relate to the first.
14.I have to get a grip on myself; she just wants to infuriate me.
15.This country is in the grip of (a) recession,I can understand it: every country has its ups and downs.
16.Sometimes I feel I am losing my grip on life,but I cannot do anything because I am too tired.