Rules 9 and 10

9. Possessive Apostrophe Error

The dogs trainer is training the dog intensely. (Incorrect)


The dog`s trainer is training the dog intensely. (Correct).


You have to add an apostrophe and an "s" to show a noun`s possession of another noun.

10. Verb Tense Shift

Last weekend, I walk to my friend`s house, and rode his bike home.


Last weekend, I walked to my friend`s house and rode his bike home


When you write a sentence, be sure to make all the verbs in the same tense.