He is now ______ on his second novel.( engaged occupiedbusy

这题只能选engaged
这句话的意思是：他现在正忙着写他第二本小说.
idle首先要排除掉,完全相反的意思.
剩下的词语都可以用来表示致力于做某事、忙于某事等等相近的意思.关键是题目中后面给的介词是on.
其他几个词在使用的时候,后面接地介词都不是on：
be occupied in doing sth
be occupied with sth
be employed in doing sth
be busy doing sth
be busy with sth
be absorbed in sth
be buried in sth
只有be engaged in/on/upon sth 可以用介词on

busy