为什么这个句子动词位于句首不用ing形式?

1、原句是(we should/ Let's) learn from them ,and success is just await us.
这是前面这个句子是个祈使句,省略了主语.
2、如果你用learning,句子就会变成learning from them ,and success is just await us.后面半句and success is just await us.是个完整的句子,但是learning from them就变成了一个名词性的成分,但是句子的主语不是我们.
你可以说We'll sucess by learning.