多项选择题 “三北”防护林体系中“三北”是指（）。

单项选择题 As we have only moderate means at hand, the tie-up of funds for ______ three to four months indeed presents a problem to us. A．as soon as B．as far as C．as long as D．as well as

单项选择题 童年期儿童游戏属于（）。