More irregular verbs:
Irregular verbs take on a special form. Unfortunately the only solution is to practice them.
Remember that there are many different irregular verbs.

Examples:
awake / awoke / awaken
uphold / upheld /upheld
undo /undid / undone
strike / struck / struck

More examples:
spread / spread / spread
sink / sank / sunk
shave / shaved / shaved
retake / retook / retaken
preset / preset / preset
grind / ground / ground