9.15÷(0.82＋1.7×0.4)=____
下列各句中，标点符号使用正确的一句是 ( )
Tom rode his motorbike to work yesterday and had a crash with a car. His motorbike was ________ and he was seriously ________.
下列关于“改革开放”理解不正确的是（）
乘法算式：____、____
除法算式：____、____
