It’s not easy to change habits，________

在滑冰场上，甲、乙两小孩分别坐在滑冰板上，原来静止不动，在相互猛推一下后分别向相反方向滑行，假定两板与冰面间的摩擦因数相同。已知甲在冰上滑行的距离比乙远，这是由于[ ]

A、在推的过程中甲推乙的力小于乙推甲的力

B、在推的过程中甲推乙的时间小于乙推甲的时间

C、在刚分开时，甲的初速度大于乙的初速度

D、在分开后，甲的加速度的大小小于乙的加速度的大小

在标准ASCII码表中，英文字母A的十进制码值是65，英文字母a的十进制码值是

A) 95
B) 96
C) 97
D) 91

挖掘作业前，应查明施工场地内明、暗铺设的各类设施，并应采用明显标识。

(31) analysis emphasizes the drawing of pictorial system models to document and validate both existing and/or proposed systems. Ultimately, the system models become the (32) for designing and constructing an improved system. (33) is such a technique. The emphasis in this technique is process-centered. Systems analysts draw a series of process models called (34) . (35) is another such technique that integrates data and process concerns into constructs called objects.

（31）是（）

A.Prototyping

B.Accelerated

C.Model-driven

D.Iterative

对机器的转动部分应有哪些防护措施？