A project planning methodology is any structured approach used to guide the project team during development of the project plan. What is an example of this methodology

A．Standard forms or template

B．Upper management involvemen

C．Functional work authorization

D．Stakeholders skill

一辆汽车沿直线运动，第1s内通过1m，第2s内通过2m，第3s内通过3m．则汽车前2s的平均速度是______m/s，前3s内的平均速度是______m/s．