64÷____ =8 30÷____ =4+1 25÷____ =15÷3
7÷____ =6÷6 35÷____ =7 45÷____ =25÷5
请你根据图中的有关信息,说说风力发电开发的困难和前景.
①____
② ____
He often fly kites.