Intro
(Just the simple root notes)
D C G
G| -------------------------------------------------------------|
D| -------------------------------------------------------------|
A| --5-5-5-5-5-5-5-5-5-5-5-5---3-3-3-3-3-3-3-3-3----------------|
E| ------------------------------------------------3-3-3-3-3-3--|
Then the rest of the song does this.
[ Tab from: https://www.guitartabs.cc/tabs/g/green_day/knowledge_btab_ver_4.html ]
A.
D C G
G| -------4-7-4-2h4p2-------------------------------------------|
D| ---4-7-------------4------2-3-5------------------------------|
A| -5----------------------3-----------2-3-4--------------------|
E| ----------------------------------3--------------------------|
B.
D C G
G| ---7-5-4-----------------------------------------------------|
D| ---------7-5-4--------2-3-2----------------------------------|
A| -5-------------7----3-------------2-3------------------------|
E| ------------------------------3-5----------------------------|
C.
D C G
G| -7-5-4-------------------------------------------------------|
D| -------7-5h7p5-4-4h5p4---------------------------------------|
A| -----------------------5----3-5-3-2-----5-3-2----------------|
E| --------------------------------------3----------------------|
Vary them around during the song and you should be fine