"Had become" is the past perfect tense of become.
The past perfect tense of "they became" is "they had become." It is used to indicate that an action or event was completed before another specified past action or time.
Have become is present perfect. Present perfect is have/has + past participle. Become is the past participle of the verb become.You have become a real problem for me
Have/has become.
The past tense of "exist" is "existed." The past perfect tense is "had existed."
The past tense of "bleed" is "bled." The past perfect tense of "bleed" is "had bled."
The past tense of sit is sat. The past perfect tense of sit is had sat.
The past perfect tense of hope is had hoped.
The past perfect tense of "submit" is "had submitted."
The past perfect tense of "confront" is "had confronted."
The past perfect tense is had rung.
The past perfect tense is had burned.