Progress has been very good so far．We are，_________, confident that the work will be completed as expected．

A．however

B．therefore

C．besides

D．otherwise

2010年潍坊兴华学校对全校学生上网情况作了一次调查。调查数据见下表：

请回答：

（1）根据调查数据，归纳说明该校学生所存在的问题。

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（2）说明我们中学生如何正确对待上网？

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