The simple past for "sink" is "sank."
Ex. The boat sank.
However, the past participle (and thus the form used in the more complex forms of the past tense) is "sunk."
Ex. The boat had sunk ten years ago. The boat will have sunk by the time you read this. The boat wouldn't have sunk if it hadn't had a hole in it. I have finally sunk the boat.
A full list of all forms can be found here: http://www.vocabulix.com/conjugation2/sink.html
The past tense of "to occur" is occurred.
Tired is an adjective it doesn't have a past tense.
Enthusiasm is a noun and doesn't have a past tense. Only verbs have a past tense.
Some examples: Past tense - worked. Future tense - will work. Past tense - played. Future tense - will play. Past tense - lied. Future tense - will lie.
Lost is the past tense of lose.
Sank is the past tense of sink. The past participle is sunk.
The past participle tense of sink is "sunk"Sunk
sunk
The past tense of sink is sank.
sunk
It is sank.
the future tense would still be sink: that ship will sink the present tense could be one of the two: sink: sink that ship! sinking: it is sinking and finally the past would be sank: i saw the ship, it sank not two days ago. hope it helps!!
Those letters spell sunk, the past tense of the verb to sink.
The present tense of "sank" is "sink."
The future tense of "sink" is "will sink".
Yes, it is the past tense of the verb sink. My boat may sink today, because my boat sunk yesterday. I need a new boat.
the past tense of am is was and the past tense of has is had