任务型教学的主要目的是（）。 A.让学生懂得任务的重要性 B.让学生在用目的语完成布

简述布鲁纳的认知结构教学理论。

佝偻病激朋X线所见为

A．骨骺与干骺端的距离多无变化
B．临时钙化带模糊
C．骨质密度正常
D．骨膜增生
E．骨骺软骨变窄

The teacher ____ the office for a few minutes when we arrived. We didn't meet him. [ ]

A. had left                    

B. had left    

C. has been away from        

D. had been away from    

防洪堤顶标高应高于洪水位( )m以上。

A．2.0
B．1.0
C．0.8
D．0.5

成人胃管插入深度一般为（）cm。