第18题: [单项选择]实体-联系模型可以形象地用E-R图表示,在E-R图中以( )图形表示实体类型。 A. 菱形 B. 椭圆形 C. 矩形 D. 三角形 参考答案:C 答案解析:[分析] 实体型用矩形表示,矩形框内写明实体名。属性用椭圆形表示,并用无向边将其与相应的实体连接起来。联系用菱形表示,菱形框内写明联系名,并用无向边分别与有关实体连接起来,同时在无向边旁标上联系的类型
A. Because we have made up our mind to do so. B. Because we want to fulfil our desire for knowledge. C. Because we want to enjoy the ecstasy of achievement. D. Because we cannot help ourselves. 参考答案:D 答案解析:[听力原文]11-13 The stun total of our knowledge is very small compared to the size of our ignoran