Give one advantage and one disadvantage of the rivers: The Ghagra,
The Gandak and The Kosi ?  

There is no river called Ghagra. There is one called Ghaggar and another called Ghaghara. Please be more specific.

Both the Gandak and the Son rivers flow through Bihar. They are very important for the agriculture of Bihar and contributes to the fertility of the soil of Bihar. On the other hand, both rivers cause floods in Bihar bringing immense misery to the people of Bihar.