【题目】We believe the time and hard work _______ in completing such an important project are worthwhile.
A．involved B．involving
C．to involve D．to be involved
在线课程【答案】A.
【解析】
试题分析：考查过去分词做定语。这里的involved相当于which is involved，which is 可省略。并且此题考查了动词词组be involved in sth涉及到某事。句意为我们相信涉及到完成这项如此重要的项目所花费的时间和努力是值得的。故选A。