prolonged

prolonged
adj [usu attrib 通常作定语]
continuing for a long time 持续很久的; 长时间的
    After prolonged questioning, she finally confessed. 她受到长时间的盘问之後, 终於承认了.
    There will be prolonged delays for rail travellers. 乘火车的旅客要长时间受阻.

牛津英汉双解词典