To cover the cooking time?
The noodles should cover the lid.As the saying goes, "cover pot noodle, open the pot filling." Though the dumplings in the water thing, but it also tells us: "face" is to cover the pot.
Of course, cover pot cooking, time is not easy too long. In general, Shougan, fine dried noodles like the pot after boiling for 1 minutes; wide noodles like the pot after boiling for 2 minutes.
Indeed, some people refuse to cover the cooking pot, even more than the pot (YU word is not the word did not do research, but does not cover the pot) time, fee and heat, the boiled noodles through, often cooked!
