Here are some examples:
Nurse
The past tense of "cleaned" does not have a double "n" because it follows the general rule of forming past tense verbs by adding "-ed" at the end. The word "clean" does not have a double "n," so when the past tense is formed, the "-ed" is simply added to the end of the base form "clean."
The past tense of drown in drowned.
That is the correct spelling of the past tense verb "levitated" (caused to rise into the air).
The past participle of the verb "require" is "required."
Scent is a synonym of smell. The past tense of send is sent.
The past tense of "subpoena" is "subpoenaed."
These can normally be verbs which are in their past simple tense. Examples include:finnedgunnedpinnedsinned
for·bid·den[fer-bid-n, fawr-] verb 1. a past participle of forbid
Horror is a noun and therefore does not have tenses: only verbs have tenses.
* nail * name * need * nest * nod * note * notice * number
That is the correct spelling of "showed" (the past tense of to show).The similar word is should, used with a verb to mean a usual or recommended action.