71, More and more people migrate from countryside to cities to find jobs.

72, Those people who can take risks is more likely to success.

Those who can take risks are more likely to achieve success.

73, The old one is too weak to work.

The old are too week to work.

74, We should find out the reason of this problem.

We should find out the reasons for this problem.

75, Governments cost a large amount of money to solve traffic congestion.

Governments spend a large amount of money in solving traffic congestion.

76, The meeting was last three hours.

The meeting lasted three hours.

77, We should avoid making the same mistakes next time.