Verbs ending in a consonant followed by -y change the -y to -ied in the past tense form.
Thereby is regular. It follows the -ied Conversion rule.
Use past time markers: "Yesterday, she therebied to the store."
No. Use "did not thereby" (not "did not therebied").
The verb thereby follows the standard English past tense conjugation rule. When forming the past tense, thereby becomes therebied. This follows the -ied Conversion pattern, which is one of the most common conjugation rules in English.
Understanding why thereby becomes therebied helps with spelling and pronunciation. Verbs ending in a consonant followed by -y change the -y to -ied in the past tense form.
When using therebied 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 therebied to the store." The past tense form does not change based on the subject — I therebied, you therebied, he/she therebied, we therebied, they therebied.