A ‣ As ... as 
As ... as similes are easy to understand. If you see the phrase as dead as a doornail, you don't need to know what a doornail is, simply that the whole phrase means 'totally dead'. But remember fixed similes are usually informal and often humorous. Those marked * are negative and could offend. Use all these expressions with care and keep them generally as part of your receptive vocabulary.
Creating a picture in your mind can often help you remember the simile:
Some can be remembered as pairs of opposites.
as heavy as lead /led/ ≠ as light as a feather
as drunk as a lord* ≠ as sober as a judge
as black as night ≠ as white as snow (particularly used in fairy tales)
Some can be remembered by sound patterns.
as good as gold (this is used about children's behaviour)
as cool as a cucumber
as busy as a bee
Some other useful phrases using as ... as:
The bed was as hard as iron and I couldn't sleep.
I'll give this plant some water. The soil's dry as a bone.
He's as mad as a hatter*. He crossed the Atlantic in a bathtub.
She told the teacher, as bold as brass, that his lessons were boring.
You'll have to speak slowly and clearly - he's as deaf as a post*.
Don't worry. Passing this exam is as easy as pie.
She knew the answer as quick as a flash.
The Princess's skin was as white as snow. [beautifully white]
When he saw it, his face went as white as a sheet. [pale with fear/horror]
The fish was bad and I was as sick as a dog. [ vomiting]
She ran off with my money - I felt as sick as a parrot. [bad feeling of disappointment/frustration]

When I told him, his face went as red as a beetroot.
Language help
You can usually make a simile using as … as can be, e.g. I need a drink; I’m as thirsty as can be.
B ‣ Like 
My plan worked like a dream and the problem was soon solved. [worked very smoothly and well]
Be careful the boss doesn't see you - she has eyes like a hawk. [sees everything]
No wonder he's fat. He eats like a horse and drinks like a fish*.
Did you sleep well? Yes, thanks, like a log.
Sorry, I forgot to ring him again. I've got a mind/head like a sieve! [be very forgetful]
The boss is like a bear with a sore head today. [in a very bad temper]
She goes around like a bull in a china shop*. [behaving in a very clumsy, insensitive way]
Criticising the government in his presence is like a red rag to a bull. [certain to make him very angry]