Give correct form of Word: What is the (long) ... of this river?

Give correct form of Word:
1, What is the (long) ........................................ of this river ?
2, I want to (long) ........................... my trousers . They are too short.
3, What is the (wide) ...................... of your house ?
4, She needs (wide) .................... her knowledge.
5, Mr Quang spent his (child) .............................. in Cambodia.