What is the meaning of deviant usage and common error ​

Common Error: Grammatical errors come in many forms and can easily confuse and obscure meaning. Some common errors are with prepositions most importantly, subject verb agreement, tenses, punctuation, spelling and other parts of speech. Prepositions are tricky, confusing and significant in sentence construction.

Deviant Usage: Someone or something that deviates from a norm especially : a person who differs markedly (as in social adjustment or behavior) from what is considered normal or acceptable social/moral/sexual deviants Those who commit crimes also watch TV, go to the grocery store, and have their hair cut.

a complex sentence consists of an independent clause and one or more dependent clauses.  

to write complex sentences, we must use subordinating conjunctions.  

all the complex sentences begin with a subordinating conjunction and when it occurs, a comma must be place at the end of the dependent clause. on the contrary, if the sentence begins with an independent clause, then no comma is used.

after  

although  

as  

because  

before  

if  

since  

when  

for example,  

after she won the competition, she became very popular.  

although my father was hurt, he continued fighting for his rights.  

as all of you got a ten, you will be able to leave early today.  

before he went to the war, he asked his parents to bless him.  

if it is cold, i won’t go out.  

since you didn’t bring the homework, you will get low grades.  

when it is hot in the town, everyone goes to the beach.