Verbs ending in -e simply add -d to form the past tense. This is the most straightforward regular rule.
Diphthongise is regular. It follows the -d Addition rule.
Use past time markers: "Yesterday, she diphthongised to the store."
No. Use "did not diphthongise" (not "did not diphthongised").
The verb diphthongise follows the standard English past tense conjugation rule. When forming the past tense, diphthongise becomes diphthongised. This follows the -d Addition pattern, which is one of the most common conjugation rules in English.
Understanding why diphthongise becomes diphthongised helps with spelling and pronunciation. Verbs ending in -e simply add -d to form the past tense. This is the most straightforward regular rule.
When using diphthongised in writing, remember that it functions as a past tense verb and typically appears with time markers like yesterday, last week, or ago. For example: "Yesterday, she diphthongised to the store." The past tense form does not change based on the subject — I diphthongised, you diphthongised, he/she diphthongised, we diphthongised, they diphthongised.