题目

The price of goods usually rises when the supply is not                                   for the demand. A. valued                       B. normal                      C. adequate                    D. average 答案：C松香在熔化过程中会：（     ）A．放热，温度不断降低B．吸热，温度不断升高C．吸热，温度不变D．放热，温度不变