掌握了加、减法的学生，容易学好乘法运算，这就是一种知识的迁移。（ ）
参考答案：对
23．- Why weren’t you at the meeting?
- I ________ for a long distance call from my sister in America.
A．was waited
B．was waiting
C．has waited
D．have been waiting
颅脑CT增强扫描，一般作为判断增强效果好坏的参考标准：（）.
A．脉络膜丛显影的好坏
B．大脑镰显影的好坏
C．小脑镰显影的好坏
D．Willi氏环显影的好坏
E．垂体腺显影的好坏
