Shut is an irregular verb the past is the same shut, so the past of shut down
is the same shut down.
They shut down the factory at 6:00pm everyday -- present.
They shut down the factory late yesterday. -- past.
Shut down
is a phrasal verb. It has two parts shut and down but they act as a single word.
shutShut is the past perfect tense (I thought I had shut the door.)It is also the simple past tense (I shut the door a few minutes ago.)"I am shutting the door" is present tense.It is also shut, please shut the door, I have shut the door.
The past participle (and simple past) is shut.
The present tense of "shut" is "shut." It remains the same in both past and present tense.
The past form of "shut" is "shut." It remains the same in both the present and past tense.
The past tense is sat down.
shutShut is the past perfect tense (I thought I had shut the door.)It is also the simple past tense (I shut the door a few minutes ago.)"I am shutting the door" is present tense.It is also shut, please shut the door, I have shut the door.
The past participle (and simple past) is shut.
The present tense of "shut" is "shut." It remains the same in both past and present tense.
The past form of "shut" is "shut." It remains the same in both the present and past tense.
The past tense is fell down.
The past tense is sat down.
The past tense is stepped down.
The past tense is downed.
The past tense of "lie down" is "lay down."
The past tense of "slow down" is "slowed down."
The past tense of "lay down" is "laid down."
The past tense of "lie down" is "lay down", and the past participle is "lain down".