子管在人（手）孔内应伸出适宜的长度，可为（）mm。

A、100~200

B、200~400

C、300~500

D、400~600

局域网中，常用的网络传输介质有（）

A、双绞线

B、同轴电缆

C、光缆

D、电话线

现有：   class Thread2 implements Runnable {   void run（） {   System.out.print（"go "）；   }   public static void main（String [] args） {   Thread2 t2 = new Thread2（）；   Thread t = new Thread（t2）；   t.start（）；   }   }   结果为：（）

A、 go

B、 编译失败

C、 代码运行，无输出结果

D、 运行时异常被抛出

You have enabled backup optimization for the RMAN environment.Identify two criteria on which RMAN will skip the file, if it has already been backed up.（）

The data file backup is done with multiple channels

The data files is in the read-write mode after being backed up in the read only mode

The backup was taken after the data files was taken offline-normal or is in the read only mode

The data file backup complies with the back retention policy and the backup duplexing feature

The RECYCLEBIN parameter is set to ON for your database. You drop a table, PRODUCTS, from the SCOTT schema.Which two statements are true regarding the outcome of this action?（）

All the related indexes and views are automatically dropped

The flashback drop feature can recover only the table structure

Only the related indexes are dropped whereas views are invalidated

The flashback drop feature can recover both the table structure and its data

Which two statements in a source NAT configuration are true regarding addresses, rule-sets, or rules that overlap?（）(Choose two.)

Addresses used for NAT pools should never overlap.

If more than one rule-set matches traffic, the rule-set with the most specific context takes precedence.

If traffic matches two rules within the same rule-set, both rules listed in the configuration are applied.

Dynamic source NAT rules take precedence over static source NAT rules.