when you consider sth 考虑到；鉴于
Given his age (= considering how old he is), he’s remarkably active.
考虑到他的年龄，他已是相当活跃的了。
Given her interest in children, teaching seems the right job for her.
考虑到她喜欢孩子，教书看来是很适合她的工作。
also used as a conjunction:
It was surprising the government was re-elected, given that they had raised taxes so much.
令人惊奇的是，政府把税收提高这么多仍再次当选了。
noun
something that is regarded or accepted as true or real : a basic fact or assumption
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In our system it is a given that all are equal before the law.
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I think we can take (it) as a given that they will support us.