pyodbc.ProgrammingError：（＆＃39; HY000＆＃39;，＆＃39; SQL包含0个参数标记，

Question

与Oracle有联系（运作良好）：

import pypyodbc as pyodbc
cnxn=pyodbc.connect("DSN=ORCL;PWD=user1")
cursor=cnxn.cursor()
cursor.execute("select * from t_v01")
s = 'sss'
f = 'fff'
cursor.execute("select * from t_v01 where t_id = ? ",[s,]) 
#works good (above)

cursor.execute("insert into t_v01 (t_id,t_type) values (?,?)",[(s,f,),] ) 

提出上述错误：pyodbc.ProgrammingError: ('HY000', 'The SQL contains 0 parameter markers,..

但是在上一步中，Python看到了参数标记＆＃34;？＆＃34;。为什么呢？