have learned是什么时态

　　Farmers have learned that they have to migrate if they want to survive.

　　农民们已经认识到，想要生存就必须外出打工。

　　Managers have learned to grapple with networking, artificial intelligence, computer-aided engineering and manufacturing.

　　经理们已经学会了如何应对联网、人工智能、计算机辅助工程和制造。

　　You are merely reciting facts that you have learned by rote.

　　你只是在背诵自己死记硬背下来的东西。

　　In the course of our trip, we have learned a great deal in all the places we visited.

　　在参观访问过程中，我们随时随地都能学到很多东西。

　　Learn a little every day and in time you'll have learned a lot.

　　每天学一点儿，日积月累也能学不少。