The past tense is x-rayed.
The past tense of feel is felt, and the past tense of speed is sped.
The past tense is vacuumed.
Scanned is the past tense of scan.
The past tense of blast is blasted.
The past tense of collide is collided.
The past tense of 'spell' is 'spelled'. 'Spelt' is also used in British English.
The past tense of "query" is spelled as "queried".
The past tense is dealt.
The past tense is "echoed."
light
There is no past tense of knew. It is the past tense of know.
In past tense, the word "enroll" is spelled "enrolled."
The past tense of scrub is scrubbed.
The past tense of "bathe" is "bathed".
The past tense of shovel is spelled shoveled.
In Australia, New Zealand and the United Kingdom, the past tense of spell is usually spelt, although spelled is sometimes used.In the USA, the more commonly used past tense of spell is spelled.
Variation is a noun - it doesn't have a past tense.