When scaling Coherence from one to two cache servers， it will not show the same scalability as two to four. Why？（）
A. Coherence uses a more efficient TCMP algorithm going from two to four cache servers
B. When going from one to two cache servers， object backups are copied across servers so work is doubled，but going from two to four is a fixed amount of work
C. Near cache is enabled with a larger quorum thus performance is improved
D. all of the above
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大宗商品的供给弹性较低，其价格是实体经济价格水平的典型代表，而实体经济物价走势与证券市场为代表的虚拟经济吸纳游资的能力呈（）
You execute the following command in your Certkiller .com production database to change the width of the CUST_NAME column of the CUSTOMERS table： ALTER TABLE customers MODIFY （cust_nameVARCHAR2 （40）） / When you execute the command， it displays the following error message： ERROR at line 1： ORA-00054： resource busy and acquire with NOWAIT specified What could be the reason for the error message？（）
A. The database instance is not available.
B. The ALTER TABLE command does not have WAIT option
C. The table or a row in the table is currently locked by another user session.
D. The database instance is busy processing other user sessions commands.
E. The CUSTOMERS table has no long running query active at the time when this request is made.
F. The server process executing the ALTER TABLE command is busy with another command executio
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