她认为咖啡因对健康有益，但这个观点是完全错误的。

Her belief that caffeine is good for health is totally ___off-base.

他的推测完全不符合实际情况。

His guess was completely ___off-base and didn't match the facts.

老板突然问起项目进展，让我们措手不及。

The boss suddenly asked about the project progress, leaving us completely ___off-base.