• Most verbs take -s in the third person singular. 

come becomes comes

order becomes orders

travel becomes travels

Some verbs have present simple spelling changes.

• Verbs that end in 'y':

Verbs that end in 'y' often change 'y' to 'ie' before 's':

• study becomes studies
• try becomes tries
• marry becomes marries
• fly becomes flies
• cry becomes cries

Note: 'y' doesn't change to 'ie' if the ending is 'ay', 'ey', 'oy', 'uy'. So, play becomes plays, say becomes says, buy becomes buys, enjoy becomes enjoys, stay becomes stays)

• Verbs that end in 's', 'sh', 'ch', or 'x':

Verbs that end in 'ss', 'sh', 'ch' or 'x' or 'z' often add 'e' before 's':

• pass becomes passes
• wash becomes washes
• teach becomes teaches

• Have, go, do and be are irregular.

have becomes has

go becomes goes

do becomes does

be becomes is

• When the verb ends in -s or -z we double the -s or -z and add -es, e.g. quiz, quizzes. These verbs are not common.