symbol plays a very important role in our life.it's very conveniet that we use a symbol instead of some other means.first of all ,symbol can go across the gap of languge.whether you can read a word or not ,you can read a symbol no matter in China or a foreign country.then symbol is much more direct and can help to notice people to pay attention.what's more symbol is very short and brief.so we would prefer to drew a symble than a very lang and complax sentence!