造成机床变形的具体原因有（）方面的。
A、设计
B、安装
C、配合
D、结合
参考答案：A
比较大小
560÷70______9
490÷70______810÷90
320÷80______5
160÷20______8
330÷30______420÷20
210÷30______210÷70．
Nobody but doctors or nurses and those ________ by Dr. Hun ________ to enter the patient's room. [ ]
A. invited; is allowed
B. are invited; are allowed
C. being invited; allowed
D. invited; are allowed
