Verified answer

The train must have an engine to start, and that is the topic sentence. The engine supplies power, as the topic sentence holds the dynamic for the rest of the paragraph. The train is made up of many different cars, so a paragraph includes a variety of sentences. These cars must be closely linked to stay together, and so the sentences in the paragraph must run smoothly and closely together.

The choo choo train runs along a well prepared and smooth track, and in this metaphor, the paragraph needs to be prepared and concise line of thought

Also, the train carries people and goods, and the paragraph carries ideas.

i agree with jessss

sometimes the train blows a lot of black smoke and pollutes any minds in the vicinity

In "Alice in Wonderland" it was asked "How is a raven like a writing desk" , a nonsense question

you sort of have an idea. what does a train do? what is it made of?

can you make an analogy (comparison to a paragraph)

What is a paragraph, how is it made?

i never understood what those crazy teachers meant with all their childish writing "helpers"