There is a mistake in each of these sentences. Underline the mistake and then correct it

there is a mistake in each of these sentences .Underline the mistake and then correct it
[1] the dirt on vegetables can cause you sick 
[2] scientists say that the life started in the ocean
[3] he gave up to smoke 2 years ago
[4] he is a fast runner . he runs fastly
[5] can i lend your pencil ?i'm sorry . i'm using it
[6] you should keep silently when they are working
[7] how many times in a day do you brush your teeth?
[8] long is worried because he has see the dentist