Explanation:
Memphis and Thebes. Both was main cities and both located on the Nile River.
Also, I don't know why, but it also says Cairo and Alexandria were both on the Nile River. I believe these two would be correct.
I think what they want is for you to add more details. For example,The boys played football,you could say Jim and Tom play football every night before dinner.
The answer is (A.) 20 seconds. A collision occurs every 20 seconds. A collision is an interaction of two or more bodies that exert forces in a very short duration. The term collision also refers to the two moving objects that collide.
