THE THIRD PERSON SINGULAR of the simple present.
The basic rule is that you add “-s” to the infinitive form.
- to run – he runs
- to eat – she eats
- to rain – it rains
After certain infinitive endings you must add “-es.”
- to go – he goes
- to kiss – he kisses
- to push – he pushes
- to touch – he touches
- to box – he boxes
- to buzz – it buzzes
If you have a consonant plus “y,” the third person ending is “-ies.”
- to try – she tries
- to fly – it flies
Note that this is not the case if the “y” is preceded by a vowel.
- to play – he plays
- to stay – she stays
Remember that the modal auxiliaries have no “s” in the third person singular.
- can – he can
- may – she may
- must – it must
THE SIMPLE PAST AND THE PAST PARTICIPLE.
The general rule is to add “-ed” to the infinitive.
- to work – I worked – you have worked
- to pass – she passed – they have passed
- to land – we landed – they have landed
After “e” just add “-d.”
- to reduce – they (have) reduced
- to receive – we (have) received
A consonant plus “y” becomes “-ied.”
- to cry – she (has) cried
- to try – I (have) tried
- to reply – you (have) replied
Note that, as before, a “y” preceded by a vowel is not modified.
- to stay – you (have) stayed
- to display – they (have) displayed
After a simple, accentuated vowel followed by a single consonant, the consonant is doubled before we add “-ed.”
- to stop – they (have) stopped
THE PRESENT PARTICIPLE.
The basic rule is to add “-ing” to the infinitive.
- to work – working
- to stand – standing
- to play – playing
- to try – trying
If the infinitive ends in a consonant plus “e,” we normally drop the “e” before adding “-ing.”
- to smile – smiling
- to hope – hoping
But don’t forget the following cases.
- to be – being
- to die – dying
- to lie – lying
- to see – seeing
As before, the consonant is doubled after a simple, accentuated vowel followed by a single consonant:
- to stop – stopping