D. Preposition: by
D1. We use to say how we do something: by post; by phone/ by email; by hand/ pay by cheque; by mistake/ by accident/ by chance etc. (not by the chance/ by a cheque). We use by + noun without the or a.
a. But we say pay cash or pay in cash (not by cash), do something on purpose (= you mean to do this) (e.g. I didn’t do it on purpose. It was an accident.)
D2. use by ~ to say how somebody travels: by car/ by road/ by rail/ by underground. (e.g. Joanne usually goes to work by bus.) But we say on foot (e.g. Did you come here by car or on foot?)
a. cannot use by if we say my car/ the train/ a taxi etc. We use by + noun without ‘a/ the/ my’ etc. by car but in my car (not by my car) by train but on the train (not by the train)
b. use in for cars and taxies (e.g. They didn’t come in their car. They came in a taxi.) Use on for bicycles and public transport (buses, trains etc.) (e.g. We travelled on the 6.45 train.)
D3. We say ‘something is done by somebody/ something’ (passive) (e.g. Have you ever been bitten by a dog?) We say a play by Shakespeare; a painting by Rembrandt; a novel by Tolstoy etc. (e.g. Have you read anything by Ernest Hemingway?)
a. Compare by and with: The door must have been opened with a key. (not by a key) (= somebody used a key to open it) vs. The door must have been opened by somebody with a key.
D4. By also means beside (e.g. Come and sit by me. (= beside me))
a. Clare’s salary has just gone up from $5,000 a month to $5,500. So it has increased by $500/ by ten percent.