若在如图1电路中将R去掉，R=6Ω，换入一只标有“8Ｖ4Ｗ”的灯泡Ｌ与一只滑动变阻器Ｒ′串联，如图2，当开关Ｓ闭合后，当滑动片Ｐ从ａ点滑到ｂ点时，电路中电阻值增大了6Ω，滑动变阻器两端的电压增加了1.6 V。求：滑动片Ｐ在b点时，灯泡的实际功率是多大?（灯泡灯丝电阻保持不变）

                                                                                           图1                            图2

The students in the international school are encouraged to voice whatever opinions they have and

question authority, which helps to develop their______ thinking. [      ]

A. cautious  

B. casual

C. careful  

D. critical