[Grammar] Please help .....if a word ends in ing is it still a verb when in the past tense

[Trev50]

In the following sentence could someone please tell me if the words walking and riding are still verbs, or have they become gerunds or nouns? Please help!!

"Yesterday I was walking to the park when I saw my friend riding her bike"

If they are still verbs...why?

So many thanks.

Trev50

 

[emsr2d2]

"I was walking" = past simple continuous (verb)
"I saw my friend [who was] riding her bike = past simple continuous (verb)