将课程看作是学习者获得的直接经验的学者是（）。
A.皮亚杰
B.斯宾赛
C.克伯屈
D.杜威
参考答案：D
He often ______ ping-pong with his friends. Now they ______ ping-pong at school.[ ]
A. play; are playing
B. plays; play
C. plays; are playing
D. plays; is playing
灵活插卡的LPUF单板无法在NE40上注册，LPUF板反复重启，可能由下列原因引起（）。
A、NE40的当前版本太低不支持LPUF单板
B、LPUF单板没有插子卡
C、NE40的相应槽位故障
D、LPUF单板BOOTROM损坏
