security risk
person who, because of his political beliefs, personal habits, etc may endanger the security of the state, eg by revealing secrets to an enemy (威胁国家安全的)危险人物
She's a poor/good security risk. 她是个不太[十分]危险的人.
OK, everyone. Less noise, please! Gather round and listen carefully. First we are going to search the beach and the rock pools. Let me remind you what we are looking for: seaweeds, fish, plants, all living things. When you find anything, make a note where