They said the eighteenth and the last lesson were quite easy.

主过从过
They said 后面省略that
that是从句引导词
用were
这是从句

They said the eighteenth and last lesson( )quite easy.
A. is B.was C.are D.were

答：选B，本题是对动词时态与主谓一致的灵活考查，由于主句谓语为said动词过去时，故从句也应用过去时，故A、C不可取。
而the eighteenth and last lesson只有一个冠词，故指同一个概念，单数概念“第十八
课即最后一课”，当然若有两个冠词则指复数概念，如：the eighteenth and the last lesson。

十八课和最后一课是两课，用复数were
They said (that )the eighteenth and the last lesson were quite easy. that引导的从句

从句的主语是the eighteenth and the last lesson ,复数概念.

他们说第十八课和最后一课都非常简单。