目前，虚拟存储的发展尚无统一标准，从虚拟存储的拓扑结构来讲主要有哪两种（）
A.对称式
B.非对称式
C.集中式
D.发散式
参考答案：A, B
根据句意及首字母提示，完成下列单词的拼写。
1. It is well known that Yao Ming is a p______ basketball player.
2. Little Tom lives s________ near our school.
3. Beijing will h________ the 29th Olympic Games.
4. English Coaching Paper is popular with (受欢迎) r________.
5. Look! Farmers are b________ their new houses.
电梯工作环境中富含（）影响不大。
A、腐蚀性气体
B、易燃性气体
C、导电尘土
D、一氧化碳
