1.be covered with基本意为盖满、被…覆盖着，是一个系表结构，强调状态；
Everything was covered with a thick layer of snow.
be covered with和be covered by用法区别精讲
The lake was covered with a sheet of ice.
The page was covered with a mass of figures.
The books were all covered with dust.
The walls were covered with pictures.
To add verisimilitude, the stage is covered with sand for the desert scenes.
His desk is covered with electronic gadgetry.
The desk was covered with papers
His legs were covered with weeping sores.
My face was covered with bruises and I had a broken rib.
His face was covered with pimples.
The whole plant is covered with fine down.
Cars were covered with clear-coat finish at the factory to protect the underlying paint from fading. 工厂给汽车上了透明罩漆，以防底漆褪色。
The square is covered with dancing people.
2. be covered by基本意为被…覆盖住，是被动语态，强调动作。
Much of the country is covered by forest.
The moon was covered by the dark clouds.
The bright moon was covered by heavy clouds.
The city is covered by a foul-smelling cloud of smoke.
The banks of the river are covered by grass.
His teeth were never entirely covered by his lips.他的牙齿从未被嘴唇完全遮住过。
These items are not covered by your medical insurance
All my living expenses and tuition will be covered by the state.
The rest of the expenses would be covered by the insurance company.
Any extended illness will be covered by insurance.
In many cases, the costs are not covered by medical insurance schemes.
Don’t judge a book by its cover.