开关电源系统应采用（）交流供电线路，从配电房直接引接，两条单独的供电线路应分别由配电房的两台变压器输出的两个空气开关输出。
参考答案：单独的双回路
同义句转换。
1. In order to catch the train, she hurried through her work.
She hurried through her work _____ _____ she could catch the train.
2. The questions are too difficult for the children to understand.
The questions are _____ difficult _____ the children can't understand.
3. The Blacks don't live in this city any longer.
The Blacks _____ _____ live in this city.
4. I think it is necessary for you to come here tomorrow.
I_____ _____ _____ necessary for you to come here tomorrow.
5. Do you know the girl who is wearing in a green skirt?
Do you know the girl _____ a green skirt?
路面结构通常分为三层，分别为（）
A.表层
B.面层
C.基层
D.垫层
