解析：
remain v. 保持不变，剩余
In spite of their quarrel, they remain the best of friends. 尽管有过争吵，他们仍是最好的朋友。
There were only ten minutes remaining. 只剩下十分钟了。
remain invincible 立于不败之地
解析：
concerned adj. 担心的，关注的
He didn't seem in the least concerned for her safety. 对她的安全他似乎一点都不担心。
They were more concerned with how the other women had dressed than in what the speaker was saying. 他们对别的女人的衣着打扮比对发言人的讲话更加感兴趣。
concerned with 关心，涉及
concerned about 关心，担忧
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