The tower is closed for reasons of safety.
There was no reason to panic.
We have reason to believe that the goods were stolen.
Under the circumstances, we had every reason to be suspicious.
二、reason+定語從句
a. 關系副詞充當定語從句的原因狀語，可以用why或that或省略。
The reason I called was to ask about the plans for Saturday. - Longman
The reason why（或者that）he doesn’t come is that he is ill. ——《英漢大詞典》
The reason that [why] he died was lack of medical care. ——《用法詞典》
That’s one of the reasons he always gets on my nerves. ——《用法詞典》
備註：關系副詞可以用for which代替。
The first question is whether the reason for which Google considered entering the wholesale broadband market in the first place still holds.
b. 關系代詞充當定語從句的主語或賓語，可以用that或which，與壹般的定語從句用法相同。
What is the reason that he gave for this?
What was the reason which led the slaves to leave the estates in British Guiana?