This structure is used to measure and compare things that are of similar proportion. In this construction, the first as functions as an adverb modifying the following adjective or adverb. The second as functions as a preposition when it relates to the following noun or pronoun.
- The meal was as good as the conversation: spicy and invigorating!
- She spoke as slowly as she could.
- Has everybody eaten as much as they want?
- I hope you will agree that I am as imaginative a cook as my wife (is)!
Note from the above example that if there is an adjective and a noun after the first as, a / an must go between them. Note also that if we want to make a negative statement, we can use so…as instead of as…as:
- He is not so / as intelligent as his sister is.
- The cafeteria was not so / as crowded as it was earlier.
There are a large number of idiomatic expressions or fixed phrases which we use in informal English when we are making comparisons like this. Here are a few of them in context:
- He went as white as a sheet when he saw the ghost.
- My maths teacher is as deaf as a post and should have retired years ago.
- She sat there as quiet as a mouse and wouldn’t say anything.
- Electricity will be restored to our homes as soon as possible.
- All the children were as good as gold when they came to visit me.
- These stories are as old as the hills and have been passed down from generation to generation.
Remember that when we are measuring or comparing things that are of unequal proportion, we need to use the structure comparative + than:
- Let me finish the report. I can type much faster than you (can). He played the piece of music more slowly than I had ever heard it played before.