8255A的端口A工作在方式2时，使用端口C的______作为与CPU和外部设备的联络信号。
参考答案：PC7～PC3
急性溶血或慢性溶血急性发作与慢性溶血不同之处为
A．出现黄疸
B．出现贫血
C．出现乏力头晕
D．出现高热，休克可伴有血红蛋白尿
E．出现心率快，气短，心前区杂音
What a pity! Considering his intelligence and diligence, he ______ a higher grade.[ ]
A. can have achieved
B. must have achieved
C. need have achieved
D. might have achieved
