下列从左到右的变形,是因式分解的是[ ]
A.x2﹣x=x(x﹣1)
B.a(a﹣b)=a2﹣ab
C.(x+3)(x﹣3)=x2﹣1
D.x2﹣2x+1=x(x﹣2)+1
答案:A
Configuration management is______.
A.used to ensure that the description of the project product is correct and complete
B.the creation of the work breakdown structure
C.the set of procedures developed to assure that project design criteria are met
D.a mechanism to track budget and schedule variances
营养性缺铁性贫血的预防措施包括()
A.提倡牛乳喂养
B.提倡母乳喂养
C.纠正偏食
D.及时添加蛋黄、豆类、肉类
E.口服铁剂