二、谓语
谓语描述主语的行为动作或具有的特征和状态。动词在句中作谓语，一般放在主语之后。谓语的构成如下：
1．简单谓语：由一个动词或动词短语构成。
Her father works in Nanjing.
2．复合谓语：(1)由情态动词或其他助动词加动词原形构成；(2)由系动词加表语构成。
They must have finished their tasks.
[例2] Later, engineers (manage) to construct railways in a system of deep tunnels(隧道), which became known as the Tube.
[分析] managed 空格处在句中充当主句的谓语动词，根据时间状语 later和定语从句的谓语动词 became可知此处应用动词的一般过去时，且 engineers与 manage之间为主动关系，故填 managed。
