The verb that changes so much!

Can you guess which verb changes so much in various situation in English?

Yes it is 'verb to be'!

In present tense, I (am), You (are), He/She/It (is), We/They (are).
In past tense, I (was), You (were), He/She/It (was), We/They (were).
In future tense, I (shall be), You (will be), He/She/It (will be), We/They (shall be).

In German, similar things happen to 'sein'.

In present tense, Ich (bin), You (bist), He/She/It (ist), We/They (sind).
In past tense, I (war), You (warst), He/She/It (war), We/They (waren).
In future tense, I (wurde sein), You (wirst sein), He/She/It (wird sein), We/They (werden sein).