and it's a big if informal PROBABLYused to say that something is not likely to happen 这是一大疑问〔用于表示某事不大可能发生〕 The team will go racing next year if – and it’s a very big if – they can raise £6 million. 该队明年会参加比赛——如果他们能筹到600万英镑的话,但这是一大疑问。
→ and it’s a big if at if2(2)