写出除法算式。

1．有12朵花，平均分给4个小朋友，每个小朋友分3朵花。

列式：                                

2．28除以4等于7。

列式：                                

（）is a method of constructing a project schedule network diagram that uses boxes or rectangles, referred to as nodes, to represent activities and connects them with arrows that show the dependencies.

This method includes following types of dependencies or precedence relationships:（）, the initiation of the successor activity, depends upon the completion of the predecessor activity.

（）, the initiation of the successor activity, depends upon the initiation of the predecessor activity.

（）is a method of constructing a project schedule network diagram that uses boxes or rectangles.

A．PDM

B．CPM

C．PERT

D．AOA