Conjugation of words ending in -re

Shekonah, 

not necessarily.

As the lesson covers, the imparfait conjugations derive from the ‘ nous ‘ form of the present tense conjugation of the particular  verb, with the notable exception of the verb ‘ être ‘. 

For “ regular - re verbs “,  that end - dre, like attendre, the nous form keeps the ‘ d ‘ and so do the imparfait forms. 

For “ irregular -re verbs “ that end in -dre, like prendre and derivatives, the ‘ d ‘ does not appear in the present tense nous form, and therefore not in the imparfait either. 

Unfortunately the word ‘ regular ‘ in the title here is limited to ‘ regular ‘ in imparfait tense, and not the more general ‘ regular ‘ in all tenses that it usually refers to.

 ( There is also debate about which verbs are regular and irregular in the general sense as noted by Laura Lawless, but that is minutiae in the overall scheme of things )

See verb conjugation tables, examples below for more 

https://www.lawlessfrench.com/verb-conjugations/attendre/

 https://www.lawlessfrench.com/grammar/regular-re-verbs/

 https://www.lawlessfrench.com/verb-conjugations/prendre/

 https://www.lawlessfrench.com/grammar/irregular-re-verbs/