there is a question mark over something/a question mark hangs over somethingUNCERTAINused to say that there is a possibility that something will not be successful or will not continue to exist 某事还是个大问号，某事尚不确定 A big question mark hangs over the company’s future. 公司的将来如何还是个大问号。
→ there is a question mark over something/a question mark hangs over something at question mark(1)