为更专门的工作for more specialized work
为晋升的前途for prospects of promotion
为更高层次的工作责任for higher responsibility
为扩大工作经验for wider experience
找一份更好的工作to seek a better job
由于雇用期满due to expiry of employment
找到了更好的工作sought a better job
由于公司倒闭due to close-down of company