Hauj lwm lawm
Xa kev nug
Yam uas pab
1.Thaum kev rov pom tam sim no, nws tuaj yeem khaws lub tsheb lub computer thiab hluav taws xob ib txwm muaj
2.4 Rov qab polarity txuas, LED yuav teeb thiab ceeb toom suab cia mus
