Which of the following are the guidelines for the construction of a network diagram?

Guidelines for constructing network diagrams:
- Each activity is represented by only one arrow
- An arrow can represent only one activity
- If two or more activities are identified with the same start & end events. Dummy activity/activities need to be introduced in the network
- Before an activity can be started all preceding activities must be completed
- The flow of diagram is from left to right
- The arrows are not to the scale
- Arrows should be straight
- Unless absolutely unavoidable, arrows should not be crossed