LCD循环显示字符串。首先在第一行显示“Hello!”，3s后在第二行显示“Welcome to LCD！”，再过3s后将第一行改为“Nice to meet you”，再过3s后将第二行改为“Good luck !”。-LCD display string cycle. First of all, in the first line　Hello! , 3s in the second line after the show　Welcome to LCD! , A few 3s will be the first line read　Nice to meet you , a few 3s will be replaced by the second line　Good luck! .