work on 中的on是副词.继续工作 .
判断方法是看结构:动词+(代词或名词)+副词 动词+介词+代词或名词 如 go on go over think over 动词+(代词或名词)+副词. 动词+介词+代词或名词 TOM likes writing with a is looking for his friend.
例句
work on
1、 继续工作,不断工作:
The director worked on in the office until ten o'clock last night.
主任昨晚在办公室工作到十点。
2、 把(螺帽等)拧上,旋进[亦作 work into, work onto]:
The nut has been worked on the spindle.
螺帽已经拧在轴心上了。