电梯的制造、安装、改造和维修括动，必须严格遵守（）要求。
A、安全技术规范
B、国家标准
C、法律法规
参考答案：A
因式分（1）8a-4a2+32 （2）（x2-5）2+8（5-x2）+16．
—It's a long story, but there are not any new words in it.
—Good! _______ it will be hard for children. [ ]
A. So
B. Or
C. But
D. And
