$6.$ The following shows three processes interacting while accessing two shared semaphores. The statements described for each process are executed sequentially, and the statements of other processes are executed interleavedly by constraints imposed by the semaphore variables. $[5$ points$]$

$(1)$ Assuming that execution stops at some point, how many times will the character $"$ C $"$ be printed? Write down the number and explain why.

$(2)$ Assuming that execution stops at some point, how many times will the letter $"$D$"$ be printed? Write the number of times and explain why.

$(3)$ Explain how many times the letter $"\backslash ($ A $\backslash )"$ is printed at least when the above processes are executed and why.

$(4)$ Explain why the string "CABABDDCABCABD" is printed when the above processes are executed.

$(5)$ Explain why the string "CABACDBCABDD" is printed when the above processes are executed.