第四题和第十八题
谢谢

第四题remove的语法
REMOVE TABLE TableName | ?
[DELETE]
参数
TableName
指定要从当前数据库中移去的表。
?
显示“移去”对话框，从中可以选择一个要从当前数据库中移去的表。
DELETE
指定从数据库中移去该表，并从磁盘上删除。
第18题select-SQL语法
SELECT [ALL | DISTINCT] 重点在这<--------
[TOP nExpr [PERCENT]]
[Alias.] Select_Item [AS Column_Name]
[, [Alias.] Select_Item [AS Column_Name] ...]
FROM [FORCE]
[DatabaseName!]Table [[AS] Local_Alias]
[[INNER | LEFT [OUTER] | RIGHT [OUTER] | FULL [OUTER] JOIN
DatabaseName!]Table [[AS] Local_Alias]
[ON JoinCondition …]
[[INTO Destination]
| [TO FILE FileName [ADDITIVE] | TO PRINTER [PROMPT]
| TO SCREEN]]
[PREFERENCE PreferenceName]
[NOCONSOLE]
[PLAIN]
[NOWAIT]
[WHERE JoinCondition [AND JoinCondition ...]
[AND | OR FilterCondition [AND | OR FilterCondition ...]]]
[GROUP BY GroupColumn [, GroupColumn ...]]
[HAVING FilterCondition]
[UNION [ALL] SELECT命令]
[ORDER BY Order_Item [ASC | DESC] [, Order_Item [ASC | DESC] ...]]
多去看看vfp的帮助文件吧，有帮助！