1.First, we need to work on the chalkboard before we can start the math.
work on 影响,对…起作用;继续工作;从事于…;设法说服
The scientists are still working on inventing new methods of reaching outer space.
科学家们仍致力于发明到达外层空间的新方法 。
The doctor told him that this kind of medicine may work on him.
医生对他说这种药对他可能有效 。