using the exact steps of the examples problems.

HI there,

I have a new HW for you ,
question 1 are in the first attachment. an examples problem are in the second attachment . i want the expert answering questions 1 using the exact steps of the examples problems. 
Questions 2: is in the third attachment. I want the expert to explains in a great details the zero force member . why members , BC,BD,BA,AD are zero force members in step 3 ???? and Why they are not any zero force member in step 4 ?????
The due date of this after is after 24 hours form now in Arizona tim