Column 1. A tour group is selecting visit locations from $A, B, C, D, E$ under the following constraints:
(1) If visiting $A$, must also visit $B$,
(2) At least one of $D, E$ must be visited,
(3) Only one of $B, C$ can be visited,
(4) Both $C, D$ must be visited or neither,
(5) If visiting $E$, both $A, D$ must be visited.
Please explain the reasoning, which places can the tour group visit at most?
堔 We adopt the貑 deduction method.
(1)
(4)
(2)
$1^{\circ}$ If going to $A \Rightarrow$ must go to $B \Rightarrow$ do not go to $C \Rightarrow$ do not go to $D \Rightarrow$ must not go to $A$. Going to $A, D$. This leads to the same contradiction as $1^{\circ}$, so do not go to $B$.
(5)
$3^{\circ}$ If going to $E \Rightarrow$ must go to $A, D$. From $1^{\circ}$, we cannot go to $A$, so do not go to $E$.
(4)
$4^{\circ}$ If going to $C \Rightarrow$ must go to $D$, and all other conditions are met. Therefore, the maximum number of places to go is $C, D$ two places.