(2011年山东潍坊模拟) 质量为60 kg的人站在水平地面上，用定滑轮装置将质量为m＝40 kg的重物送入井中．当重物以2 m/s²的加速度加速下落时，忽略绳子和定滑轮的质量及定滑轮的摩擦，则人对地面的压力大小为(g取10 m/s²)(　　)

如图所示，虚线PQ、MN间存在水平匀强电场，一带电粒子质量为m=2.0×10^﹣11kg、电荷量为q=+1.0×10^﹣5C，从a点由静止开始经电压为U=100V的电场加速后，垂直于匀强电场进入匀强电场中，从虚线MN的某点b（图中未画出）离开匀强电场时速度与电场方向成30°角．已知PQ、MN间距为20cm，带电粒子的重力忽略不计．求：

清代乾隆八年，唐英所著的20幅《陶治图说》描绘了制瓷业的20道工序；景德镇的《浮梁县志》又记载了22种制瓷业工种。这些记载可用于解释当时中国制造业（    ）

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    My husband and I were paying a visit  ____ my parents in Tucson. We went to a fast-food restaurant for dinner together. My husband went to the counter ____ (order )dishes and I stood with my parents.
    My dad is 90 ____ (year) old. He can hardly see very well and walks with a stick. I was scanning the restaurant, ____ (wait) to sit at the first table that was more convenient than others. A woman who was ____ (sit) with her son made eye contact with me and asked me to come to her. With a puzzled look on my face, I pointed to  ____ (me) and said , “Me ?” She nodded and said , “ Yes, you.” I walked to the table and she said , “ Bring your family here. I can finish eating at the counter. My son is in ____ hurry to leave anyway.” My eyes ____ (fill)with tears as she wiped down the table and guided my dad to the seat.
    I always believe that there are____ (nature) kind people in this world. This woman has set a good example to her son, ____ is a really lucky guy.

结合材料，运用所学知识回答问题：

材料：“墨子号”成功发射。2016年8月16日1时40分，我国在酒泉卫星发射中心用“长征二号丁”运载火箭成功将世界首颗量子科学实验卫星“墨子号”发射升空。这使我国在世界上首次实现卫星和地面之间的儿量子通信，构建天地一体化的量子保密通信与科学实验体系。

    “长征五号”运载火箭成功发射。2016年11月3日20时43分，我国首枚大型运载火箭“长征五号”在海南文昌航天发射场发射成功，标志着中国正式迈入拥有大型运载火箭国家的行列，空间进入能力获得大幅提升。