1. Known grammar:
S->a|^|(T)
T->T,S|S
Analysis sentence (T, (^, a)), find all phrases, phrases and handle directly.
A: The following syntax tree
All phrases: ^ a ^, a (^, a) T, (^, a) (T, (^, a))
Direct phrases: ^ a
Handle: ^
2. The context-free grammar structure description language:
(1) ｛anbn|n>=0｝
(2) ｛ambn|m>=n>=0｝
(3) if the statement
The if statement
答：(1). G[S]: S->aSb | ab | ε
(2). G[S]: S->aSb | a | ε
. (3) if the statement -> if <condition> then <statement> | if <condition> then <statement> else <statement>