不定项选择 The boy couldn’t tell how oysters tasted just by looking at them.

单项选择题 In reading stories we anticipate what is to come ________ on our memory of what has gone before. A. based B. basing C. to base D. to be based

单项选择题 是单一的绝缘结构，构成绝缘层的绝缘材料不能够拆分成基本绝缘、附加绝缘等（ ） A. 基本绝缘 B. 附加绝缘 C. 双重绝缘 D. 加强绝缘