一、基础达标训练
1．The library is believed ________ (build) in the late Qing Dynasty.
【答案】to have been built
【详解】
考查非谓语动词。句意：人们认为这家图书馆建于清朝末年。此处为短语be believed to do sth.，且build动作已经完成时，与library构成被动关系，故用to have been done形式。故填to have been built。
2．Since the concept introduced in the session is complex, students are given some time ________(digest) it.
【答案】to digest
【详解】
考查非谓语动词。句意：因为课程中介绍的概念很复杂，学生需要一些时间来消化它。结合句意表示“给某人时间做某事”可知短语为be given time to do sth.。故填to digest。
