must 有非推测性用法和推测性用法两种情态意义，变否定句的方法不同。 ▲非推测性用法的must表示义务，情态意义为“必须”。 He must finish his homework befor...
Must变为否定句，通常变为don't/doesn't have to 或者don't/doesn't need to或needn't do或can't. 因为must的否定形式mustn&#...
