各用户必须妥善保管自己的密码，第一次登录系统后必须立即更改密码；以后至少（）更改一次自己的密码。
A、7天
B、半个月
C、一个月
D、二个月
参考答案：D
根据句意及汉语意思完成句子。
1．Peter is an________（积极的）boy. He takes part in many activities.
2．My grandfather likes _________（木制的）bed because he thinks it's so comfortable.
3．Many young people_________（梦想）of becoming famous basketball players.
4．Do you know what the________（目标）of basketball is?
5．Charles is a careless boy. He often________（犯错误）in his homework.
2，8，25，66，( )
A．98
B．104
C．135
D．157
