H. As = at the same time as. The structure of the sentence is usually: as + subject + verb
H1. You can use ‘as’ when two things happen at the same time.
H2. also use just as (= exactly at that moment)
H3. use of as is to say what the role/function of a person/thing is.
I. Because is more common than as and since, both in writing and speaking. When we use because, we are focusing on the reason.
I1. We often put the because-clause at the beginning of a sentence, especially when we want to give extra focus to the reason. We use a comma after the because-clause.
J. We often use as and since when we want to focus more on the result than the reason. As and since are more formal than because. We usually put a comma before since after the main clause.
J1. We often use as and since clauses at the beginning of the sentence. We use a comma after the as- or since- clause.
J2. We use because, not as or since, in questions where the speaker proposes a reason.