93. The diligent student refused the helpof others and insisted on working out the difficult maths problem _____.

Is it cheap ______ from Qingdao to Beijing by train

Did you watch the football match yesterday—Yes, I did. You know, my brother in the match.

My mom once worked in a very small village school, which is _____ only on foot. [ ]

______ the aids from the outside, the positive attitude of the disaster-stricken people _____ the key role in the reconstruction of their destroyed towns and villages[ ]