第203句 遗忘
over a period of no practice what has been learned tends to be forgotten; and the adaptive consequences may not seem obvious.
译文：有一段时间不实践，学到的东西往往就会渐渐遗忘；其适应性结果也就显得不太明显。
点睛：本句是个并列句。在分号前面的分句中，over a period of no practice作时间状语，主语是从句what has been learned，谓语是tends to be forgotten.而分号之后的分句则是主系表结构。