Paul's poor performance in the interview was a big ______.to his mother,who had wanted her son to study at Harvard University
act
blow
sign
air
【考情点拨】本题考察名词辨析
【应试指导】句意：保罗面试表现糟糕，这对一心想让儿子上哈佛大学的母亲来说是一个重大打击。act意为“行为、行动”；blow意为“打击、挫折”a big blow to sb.是固定用法，意为“对某人的沉重打击”；sign意为“迹象、征兆”；air通常作为不可数名词，意为“空气”。故选B