Verbs ending in -e simply add -d to form the past tense. This is the most straightforward regular rule.
Diagnose is regular. It follows the -d Addition rule.
Use past time markers: "Yesterday, she diagnosed to the store."
No. Use "did not diagnose" (not "did not diagnosed").
The verb diagnose follows the standard English past tense conjugation rule. When forming the past tense, diagnose becomes diagnosed. This follows the -d Addition pattern, which is one of the most common conjugation rules in English.
Understanding why diagnose becomes diagnosed 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 diagnosed 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 diagnosed to the store." The past tense form does not change based on the subject — I diagnosed, you diagnosed, he/she diagnosed, we diagnosed, they diagnosed.