unannounced
🇺🇸
/ˌʌnəˈnaʊnst/
🇬🇧
/ˌʌnəˈnaʊnst/
adjective
R
Not previously mentioned or expected; arriving or occurring without warning.
The teacher made an unannounced visit to our class to check our progress.
老师未经宣布就来我们班级检查我们的进度。
translation
突袭