false alarm

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++ˌfalse aˈlarm noun [countable]  MISTAKEa situation in which people wrongly think that something bad is going to happen 虚惊，假警报 Fire fighters responded to a false alarm at one of the college dormitories. 消防员因学院一间宿舍谎报的火警而出动。 The patient was okay – it was a false alarm. 病人没问题——是虚惊一场。

Examples from the Corpus

false alarm• Your apprehension is based on the fear that the change might be a false alarm.• But the patient was okay, it was a false alarm, please thank them and send them on their way.• Those genes would produce a harmless protein that, once inside the body, would sound the false alarm of infection.

ˌfalse aˈlarm nounChineseSyllable  

which Corpus something that situation think people in is wrongly a bad

false alarm
ˌfalse aˈlarm noun [countable]
a situation in which people wrongly think that something bad is going to happen:
    Fire fighters responded to a false alarm at one of the college dormitories.
    The patient was okay – it was a false alarm.

false alarmBrE /ˌfɔːls əˈlɑːm/ 🔊NAmE /ˌfɔːls əˈlɑːrm/ 🔊 nouna warning about a danger that does not happen; a belief that sth bad is going to happen, when it is not 假警报；虚惊◆The fire service was called out but it was a false alarm. 消防人员接到报警后出动，但这是假报火警。🔊🔊