If there is a lot of work I’m happy to just keep on until it is finished．A. to doB. to b

网友回答

A. to do
B. to be doing
C. done
D. doing
解析：此处to do在句中做定语修饰work，本句的意思是：如果有很多工作要做，我很乐意一直把它做完。不定式做定语往往表示未发生的动作，放在被修饰词的名词、代词后。