下列句子中，每句都有一个错误，请找出错误之处并改正。

1. The price in this city is very expensive. ______

2. We must do all we could help those who are in difficulty.______

3. This is the river which I used to swim when I was a student.______

4. This is one of the best film I have ever seen.______

5. China now can produce the fastest computer of modern time.______

海洋运输货物保险的索赔时效，从被保险货物在最后的卸载港全部卸离海轮后起算最多不超过两年。