K-F环
参考答案：肝豆状核变性的患者，其眼部表现为角膜缘后弹力层常有铜盐沉积而引起金黄色或棕绿色的色素环，宽2～3 mm。
债券的票面利率是指债券发行者______占票面金额的比率。
Some people say that Mars should be protected as a wildlife reserve where we do everything possible to avoid pollution, on the _______ that life could exist on it.
A．assumption
B．arrangement
C．assistance
D．appointment
