Question

To conjugate a verb ending in -er, as in correr, what would you do first?

Add the verb endings -o, -as, -a, -amos, -áis, or -an to the stem.
Drop the -rer from the infinitive, leaving the stem cor.
Add the verb endings -o, -as, -e, -emos, -áis, or -an to the stem.
Drop the -er from the infinitive, leaving the stem corr

Answer 1

you wold drop the ending -er and replace it for -o -as -a -emos -áis -an if your conjugating it in the present tense if your conjugating it in the past tense then it's
-í -iste -ió -imos -isteis -ieron