Though Bill is very young，he has a lot of ______ about Chinese history．（　　）

I'm sorry I took your card by mistake，but where is ______？（　　）

We are going to have a party ______ the evening of June 30th．（　　）

He tried many ways to solve the problem．But ______ of them worked．（　　）

New energy cars have been ______ to cut down air pollution．（　　）