Choose the correct sentence.

1. A) Changes to the exam format could have a serious influence on candidates.

B) Changes to the exam format could have a serious effect on candidates.

2. A) It is difficult to assess the impact of the disaster on tourism.

B) It is difficult to assess the extent of the disaster on tourism.

3. A) The effects will only be seen over a long duration.

B) The effects will only be seen over a long period of time.

4. A) Managers are expected to work for a long time.

B) Managers are expected to work for long hours.