He was the legal heir to the throne.

他是王位的合法继承人.

《简明英汉词典》

He is the only legal heir of the rich man.

他是这位富翁的唯一法定继承人.

互联网

Prince Charles is the legal heir of the crown.

查尔斯王子是王位的合法继承人.

互联网

They adopted him as their legal heir.

他们立他为他们的法定继承人.

互联网