learn to do/learn doing

两个句子都是正确的。但它们的用法有区别。学习某个具体课程时，通常用 $\mathrm{<span\; class="latin-run">l</span>}\mathrm{<span\; class="latin-run">e</span>}\mathrm{<span\; class="latin-run">a</span>}\mathrm{<span\; class="latin-run">r</span>}\mathrm{<span\; class="latin-run">n</span>}+\mathrm{<span\; class="latin-run">v</span>}$learn + v -ing，但也可用 $\mathrm{<span\; class="latin-run">l</span>}\mathrm{<span\; class="latin-run">e</span>}\mathrm{<span\; class="latin-run">a</span>}\mathrm{<span\; class="latin-run">r</span>}\mathrm{<span\; class="latin-run">n</span>}+\mathrm{<span\; class="latin-run">t</span>}\mathrm{<span\; class="latin-run">o</span>}-\mathrm{<span\; class="latin-run">v</span>}$learn + to-v 。但是，学会某种技能时，则只能用 $\mathrm{<span\; class="latin-run">l</span>}\mathrm{<span\; class="latin-run">e</span>}\mathrm{<span\; class="latin-run">a</span>}\mathrm{<span\; class="latin-run">r</span>}\mathrm{<span\; class="latin-run">n</span>}+\mathrm{<span\; class="latin-run">t</span>}\mathrm{<span\; class="latin-run">o</span>}-\mathrm{<span\; class="latin-run">v</span>}$learn + to-v 。

1. She goes to college twice a week to learn typing. 她每周两次去学院学习打字。

2. Lots of people have never learnt to swim. 许多人从未学过游泳。

3. When my father was 50, he finally learned to drive. 我爸爸50岁时终于学会了开车。learn $^{2}$