Cyn cael cinio             Before having dinner
Ar ôl cyrraedd             After arriving

Ond, bydd rhaid defnyddio 'i' gyda rhagenw personol:

Cyn i fi gael cinio               Before I have dinner
Ar ôl iddi hi gyrraedd         After she arrives

Pan fyddwn ni'n defnyddio 'i' gyda ‘cyn’ ac ‘ar ôl’, rhaid cofio bod yr ymadrodd yn gallu cyfeirio at sawl amser - y presennol, y perffaith, a'r gorffennol, e.e.

Dw i’n mynd (I go/I am going)          Cyn i fi fynd (Before I go)
Dw i wedi mynd (I have gone)          Cyn i fi fynd (Before I’ve gone)
Es i (I went)                                       Cyn i fi fynd (Before I went)

Fel arfer, byddwch chi'n deall o'r cyd-destun beth yw'r amser priodol.

Mae rhai geiriau eraill sy'n dod o flaen 'i', e.e.

Nes (until)                              Nes i fi fynd (Until I go/went)
Rhag ofn (in case)                 Rhag ofn i ni ddod (In case we come/came)
Erbyn (by the time that)         Erbyn i ti gyrraedd (By the time that you arrive/arrived)

* Dychmygwch y cwestiwn 'Cyn i fi fynd? 'Fory?' ('Before I go? Tomorrow?'). Nid oes berf ar ddechrau'r cwestiwn hwn ond y gair 'cyn', ac felly, nid 'brawddeg lawn' ydy. Rhaid ateb cwestiynau fel hyn gan ddefnyddio 'Ie/Nage'.

Gair bach defnyddiol arall - Wedyn - Then / Afterwards

Aeth hi wedyn i'r sinema
Then she went to the cinema / She went to the cinema afterwards
Wedyn byddwn ni'n cwrdd â hi
Then we'll meet her / We'll meet her afterwards

Cyn cael cinio                         Before having dinner
Ar ôl cyrraedd                         After arriving

But ‘i’ must be used with a personal pronoun:

Cyn i fi gael cinio                    Before I have dinner
Ar ôl iddi hi gyrraedd             After she arrives

When ‘i’ is used with ‘cyn’ and ‘ar ôl’ it covers several tenses - present, perfect and past e.g:
Dw i’n mynd       (I go/am going)         Cyn i fi fynd  Before I go
Dw i wedi mynd (I have gone)            Cyn i fi fynd  Before I’ve gone
Es i                     (I went)                     Cyn i fi fynd  Before I went

The context usually tells you which tense it is.

There are other words which are used in this way with ‘i’ e.g.:

Nes (until)                               Nes i fi fynd                 (until I go/went)
Rhag ofn (in case)                  Rhag ofn i ni ddod      (in case we come)
Erbyn (by the time that)          Erbyn i ti gyrraedd      (by the time that you arrive)

*Any question that does not start with a verb/is not a proper sentence,e.g  Cyn i fi fynd?  ’Fory?) is answered with Ie/Nage.

Another useful little word - Wedyn - Then / Afterwards

Aeth hi wedyn i'r sinema
Then she went to the cinema / She went to the cinema afterwards
Wedyn byddwn ni'n cwrdd â hi
Then we'll meet her / We'll meet her afterwards