mail carried by aircraft, which is faster but more expensive
文法句型
by surface mail
send something (by) surface mail
用法筆記
Almost always uncountable; most commonly appears after 'by' (by surface mail). The phrase refers to the service itself, so 'by surface mail service' sounds unnatural.
常見錯誤
I sent it by surface mail service.
I sent it by surface mail.
'surface mail' already names the service; adding 'service' sounds redundant.