He has forgotten what ______ are involved and the time taken ______ delivery. ( )

A．formalities, in

B．procedures, for
C．formalities, for

D．procedures, in

根据皮亚杰的认知发展理论，儿童同时可以从两个或两个以上角度思考问题这一特征表明儿童认知水平处于（）

A．感知运动阶段

B．前运算阶段

C．具体运算阶段

D．.形式运算阶段