Complex sentence: Askari joined the department of English at Kushtia Islamic University, Bangladesh as a lecturer in July 1990, was promoted to professorship in 2005 and was head of the English department more than once.
Split into simpler sentences: Askari joined the department of English at Kushtia Islamic University, Bangladesh as a lecturer in July 1990. He was became a professor in 2005 and was head of the English department more than once.