Concrete Mixers by Patricia Hubbell

The drivers are washing the concrete mixers;
Like elephant tenders they hose them down.
Tough gray-skinned monsters standing ponderous,
Elephant-bellied and elephant-nosed,
5 Standing in muck up to their wheel-caps,
Like rows of elephants, tail trunk.
Their drivers perch on their backs like mahouts,
Sending the sprays of water up.
They rid the trunk-like trough of concrete,
10 Direct the spray to the bulging sides,
Turn and start the monsters moving.
Concrete mixers
Move like elephants
Bellow like elephants
15 Spray like elephants,
Concrete mixers are urban elephants,
Their trunks are raising a city.

What are the concrete mixers compared to?
What are the parts of the concrete mixers compared to?
What are the drivers of the concrete mixers compared to?
How are the comparisons related?

Tough gray-skinned monsters standing ponderous

Elephant-bellied and elephant-nosed,

trunk-like trough of concrete,

Oh! Thank you so much!

You are very welcome.

You're right. But I still can't figure out "What are the parts of the concrete mixers compared to"

Which line from the poem best indicates the theme of the poem?

I didn't understand they did the trunk like through of concrete

Come on! If you read this poem, certainly you can answer at least half of these questions!