WASHINGTON — President-elect Donald J. Trump made many sweeping promises on his way to victory on Election Day. After he takes the oath of office on Jan. 20, here are five of the most difficult and five of the easiest promises to keep:

THE DIFFICULT ONES

Prevent American companies from moving jobs to other countries.

Companies move to other countries to pursue higher profits, and Mr. Trump cannot force them to stay. The question is whether he can make it profitable to do so. It is difficult because labor is much cheaper in other countries. Carrier pays workers at its Indiana factory an average hourly wage of $23 — roughly four times what it plans to pay workers with the same jobs in Mexico.

Mr. Trump has promised tax cuts and regulatory relief, but those are minor expenses for most companies, particularly in comparison to their payrolls. Mr. Trump also has threatened to impose new taxes on imports, but he cannot target particular companies. Any such tariffs would have to be broad — and therefore broadly painful.

Revive American steel-making and coal-mining industries.

The productivity of the American coal industry has increased roughly tenfold since the end of World War II. The work that once required 10 miners now requires just one. Steel making has undergone a similar transformation. That is by far the most important reason employment in both industries has declined precipitously. Most of those jobs are never coming back.

Demand for coal has also declined thanks to a revolution in the production of natural gas and, to a lesser extent, other alternative energy sources. This, too, is a development that Mr. Trump lacks the power to reverse.