题目

III   完型填空       15% Reports about stolen virtual property(虚拟财产), (for example, the money that is gained through Web games,) are becoming increasingly frequent.         Who is responsible(负责任的) for this?        “Virtual property theft(偷窃) is __31__ today all over the world,” __32__ professor Greg Lastowka, an American specialist in internet law.   Though a few cases have managed to make it to the courtroom(法庭), most of the time __33__ are not reported or not followed up. “local police are __34____ confused by virtual theft, thinking it建筑工人用如图所示的定滑轮装置运送建筑材料。质量为70kg的工人站在地面上，通过定滑轮将20kg的建筑材料以0.5 m/s2的加速度拉升，忽略绳子和定滑轮的质量及定滑轮的摩擦，则工人对地面的压力大小为(g=10m/s2) （       ）A．510 NB．490 NC．890 ND．910 N