PRESENT TENSE:
- THEY SWIM TODAY
-THEY DON'T SWIM TODAY
- DO THEY SWIM TODAY

PAST TENSE:
- THEY SWAS YESTERDAY
-THEY DINDN'T SWIM YESTERDAY
- DID THEY SWIM YESTERDAY

PRESENT PROGRESSIVE
-THEY'RE SWIMMING NOW
- THEY'RE NOT SWIMMING
-ARE THEY SWIMMING NOW

PAST PROGRESSIVE
-THEY WERE SWIMMING LAST WEEK
- THEY WEREN'T SWIMMING LAST MONT
-WERE THEY SWIMMING LAS YEAR

FUTURE WILL 

-THEY'LL SWIM TOMORROW 

- THEY WONT SWIM NEXT WEEK

- WILL THEY SWIM NEXT YEAR

BE GOING TO

- THEY'RE GOING TO SWIM TOMORROW 

- THEY'RE NOT GOING TO SWIM NEXT WEEK

- ARE THEY GOING TO SWIM NEXT YEAR