设备安装位置应符合工程设计要求，其偏差不大于（）。 ["1","5","10","20"]
You need to change the definition of an existing table. The COMMERCIALS table needs its DESCRIPTION column changed to hold varying length characters up to 1000 bytes. The column can currently hold 500 bytes per value. The table contains 20000 rows. Which statement is valid?（） ["ALTER TABLE commercials MODIFY (description CHAR2(1000));","ALTER TABLE commercials CHANGE (description CHAR2(1000));","ALTER TABLE commercials CHANGE (description VARCHAR2(1000));","ALTER TABLE commercials MODIFY (description VARCHAR2(1000));","You cannot increase the size of a column if the table has rows."]
下列花卉中不属于块茎类的是（）。 ["马蹄莲","大丽花","花叶芋","大岩桐"]
什么是脱火现象和回火现象？
汽车牵引支承参数的评价指标是（）、（）和（）。
弹性润滑机理
