Just like new-born babis do. They listen, they look, and then they imitate without any hesitation in the grammer.Sometimes, I feel realy stupid to learn quite a few grammer rules.I can't use most of them in daily life.What appear in my communication with other people are always very simple and short praises and idioms.But many students around me care about grammer much more than how well you use them, I mean to speak. Most of them are not able to communicate with english spaeker, what is worse, it seem that they didn't realise the importance of speaking. their pronunciation is not correct, but they just ignore it, they spend a lot of time in the exercises of grammer, discussing a lot of complex questions like they are professors. But the fact is they even can't tell others how they think in a correct way, they are bookworms,for me , it's obvious that this kind of learning way is really not good for english learners.