关于谓语的问题

1 I like walking. like walking is 谓语. like is only a 系动词 here.
2 I made your birthday cake last night. made is 谓语
3 It is used by travellers and business people all over the world.
is used is 谓语

1:like
2:made
3:uesed

1 walking
2 made
3 used

1.like
2.made
3.be used

1:like
2:made
3: is used