However, "ea" is not a common past tense marker in English. The most common way to form the past tense in English is by adding -ed to the end of a verb. For example:
* walk -> walked
* play -> played
* jump -> jumped
There are some irregular verbs that have different past tense forms, but "ea" is not a common part of these irregular forms.
Could you clarify your question? Perhaps you are thinking of a specific word or grammatical pattern where "ea" might be used as a past tense marker?