Grammar Girl here.

Today's topic is the Complex Compound Sentence.

Guest writer Sal Glenn writes,

Most writers worth their fingertip calluses begin as avid readers.

We read books, magazines, and websites indiscriminately until we start to notice the writing itself

and marvel at the many forms a sentence can take.

The Complex Compound Sentence, spinning in the whirl of words, elicits the most admiration

in envy, how can I write like that?

First, start small.

The declarative sentence is the building block of writing.

It requires a simple string of one subject and one predicate,

and usually has one direct object.

Henrik scrubbed the goat.

Henrik is the subject, scrubbed is the predicate,

and the goat is the direct object.

All the necessary information is there,

but your reader will go for a nap if you write too many short declarative sentences in a row.

Henrik scrubbed the goat, period.

He danced a tarantella, blah.

But those two declarative sentences are related to each other

because they're both about Henrik.

So you can combine them to make a compound sentence.

...