1. He has an optical defect.
    他有种视力缺陷。

2. He has an optical defect.
    他有种视力缺陷。

3. Or consider an example raised by Judge Richard Posner: a couple in which the husband has some unfortunate genetic defect.
    或者不妨考虑一下理查德·波斯纳法官举出的例子：有一对夫妇，丈夫不幸有某种基因缺陷。

4. It was his chief defect.
    这是他的主要缺点。