Question

毫无疑问他们将提前完成这项工作。

误：There is no doubt whether they will finish the work ahead of time．

正：There is no doubt that they will finish the work ahead of time．

Answer 1

答案：
解析：

doubt用于否定句和疑问句时，其后的从句用that引导，不用if或whether；doubt用于肯定句时，从句常用if或whether引导。如：I doubt if this is what he wants．我看这不见得是他所要的。