Suppose they did not believe him, what would they do to him? 要是他们不相信他,他们会对他怎样?
What if it rains?; Suppose it rains? 要是下雨怎么办?
牛津高阶第八版
美国韦氏词典
Dictionary.com
Free Dictionary
维基百科 (自由的百科全书)