Table: secr_l_class
Columns: secr_no
sr_no
br_no
builder
date_delivered
date_withdrawn

Question: What is the withdraw date for secr no. 771?
SQL: SELECT "date_withdrawn" FROM secr_l_class WHERE "secr_no" = 771

Question: Who is the builder for br no. 31779?
SQL: SELECT "builder" FROM secr_l_class WHERE "br_no" = 31779