Complex sentence: At Serangoon Gardens Secondary School, he played for the school football team, but neglected his studies and was retained, thus he transferred to the Singapore Vocational Institute and obtained a National Trade Certificate 3.
Split into simpler sentences: At Serangoon Gardens Secondary School, he played for the school football team, but neglected his studies and was retained. He then transferred to the Singapore Vocational Institute and obtained a National Trade Certificate 3.