Question

Identify the inflection of the verb to climb.

Answer 1

1. Infinitive tense is the verb in the 'to' form, so you got it right there: to climb.
2. Third person singular present tense is the present tense plus the letter 's' at the end because it is in third person.: climbs
3. Past tense is something that happened in the past: climbed
4. Participle is like the -ing form.: climbing

Answer 2

Hi !

to climb is infinitive 
"to" before a verb is the mark of the infinitive.

That's how it's  learned in foreign countries .....

hope  I helped