These words all describe feeling or showing fear.以上各词均形容害怕。
afraid[not before noun] feeling fear; worried that sth bad might happen指害怕、担心不幸的事可能发生：◆There's nothing to be afraid of.没有什么要害怕的。◆Aren't you afraid (that) you'll fall?你不怕会跌倒吗？
frightenedfeeling fear; worried that sth bad might happen指害怕、担心不幸的事可能发生：◆a frightened child受惊的孩子◆She was frightened that the glass would break.她担心玻璃会破碎。
scared(ratherinformal) feeling fear; worried that sth bad might happen指害怕、担心不幸的事可能发生：◆The thieves got scared and ran away.小偷慌张起来，都跑掉了。
afraid, frightened or scared?用 afraid、frightened 还是 scared？
Scared is more informal, more common in speech, and often describes small fears. Afraid cannot come before a noun. It can only take the preposition of, not about. If you are afraid/frightened/scared of sb/sth/doing sth or afraid/frightened/scared to do sth, you think you are in danger of being hurt or suffering in some way. If you are frightened/scared about sth/doing sth, it is less a fear for your personal safety and more a worry that sth unpleasant might happen. * scared 较非正式，较常用于日常谈话中，常指有些害怕。afraid 不用于名词前，只能与介词 of 而非 about 连用。be afraid/frightened/scared of sb/sth/doing sth 或 be afraid/frightened/scared to do sth 均指担心受到伤害或遭受痛苦。be frightened/scared about sth/doing sth 较少指担心个人安全，更多的是指害怕不快的事情发生。
terrifiedvery frightened指恐惧、很害怕：◆I was terrified (that) she wouldn't come.我很害怕她不来。◆She looked at him with wide, terrified eyes.她看着他，双目圆睁，充满恐惧。
alarmedafraid that sth dangerous or unpleasant might happen指担心危险或不快的事情发生：◆She was alarmed at the prospect of travelling alone.她一想到独自旅行的情景就害怕。
paranoid(ratherinformal) afraid or suspicious of other people and believing that they are trying to harm you, in a way that is not reasonable指多疑、不合情理地恐惧：◆You're just being paranoid.你只是在疑神疑鬼。