Though it rained heavily, were still playing on the playground.
A. they
B. them
C. their
D. themselves
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Sorry, I can’t answer your questions. I know ______ about the subject.
A. a little
B. little
C. few
D. a few
They received of letters about their TV programs.
A. dozen
B. dozen and dozen
C. score
D. dozens
How many birds can you see in the trees？-- I can see birds in them.
A. hundreds of
B. five hundreds
C. hundred of
D. five hundreds of
以下关于索引描述中,错误的是( )。
A. 一个基本表可以创建多个索引
B. 索引可以提高数据查询的速度
C. 删除索引可以使用DROP INDEX语句
D. 索引越多越好
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