他的结论建立在一个未经证实的假设上。

His conclusion was based on an unverified ___assumption.

新经理上任后，立刻承担起了部门的管理职责。

The new manager's ___assumption of departmental responsibilities took effect immediately.

不要对你的同事下这样的武断结论，你根本不了解他。

Don't make such negative ___assumptions about your coworker when you don't even know him.