Sentence Structure and Punctuation

Basic English Sentence Structures

S – V S – V – O S – V – IO – DO

Jack is sleeping.  Jack ate an apple.  Jack gave Jill a ring.

S – LV – Adj.  S – LV – Adv S – LV – Noun

Jack is sick.  Jack is here. Jack is a doctor.

Combinations: One verb or one subject (no comma)

S V S and S V S V and V S V O and O S and S V O and O

Jack is drinking. Jack and Jill are drinking. Jack is eating and drinking. Jack drinks coffee and tea. Jack and Jill drink tea and coffee.

Combinations: Two subjects, two verbs

Subordination (One idea is stronger.)

Jack drinks coffee although Jill drinks tea. (without a comma)

Although Jack drinks coffee, Jill drinks tea. (with a comma)

Coordination (equal ideas, with coordinator: and, but, or, nor, for, so, yet)

Jack is drinking, and Jill is eating. (A comma [,] is needed here.)

Jack drinks coffee, but Jill drinks tea. (closest connection between ideas)

Closely related ideas (without coordinator)

Jack drinks coffee; Jill drinks tea. (A semi-colon [;] is used here.)

Jack drinks coffee; however, Jill drinks tea. (with a sentence connector)

Separate sentences (strongest break between ideas)

Jack drinks coffee. Jill drinks tea. (Use a period [.] to separate complete sentences.)

Jack drinks coffee. However, Jill drinks tea. (with a sentence connector) 
Jack drinks coffee. Jill, however, drinks tea. (variation)

Note:
Do not use subordinators and coordinators to connect ideas in the same sentence:

Although Jack drinks coffee, but Jill drinks tea. Jack drinks coffee, but Jill drinks tea. Although Jack drinks coffee, Jill drinks tea.

(INCORRECT) (Okay) (Okay)