如图（甲）所示，物体甲重30N，被50N的水平压力F_甲压在竖直墙壁上保持静止．如图（乙）所示，物体乙重60N，在40N的水平拉力F_乙作用下，沿水平桌面匀速向右运动．则物体甲受到的摩擦力f_甲和物体乙受到的摩擦力f_乙分别是（　　）

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    “What is the most important part of your body?” My mother asked me a question one day. “Sound is very important to us, so it's my 1 , Mommy.” I answered.

    She said, “No. Many people 2 deaf(耳聋的), but they can live by themselves and even work. You can think 3 it and I will ask you again.”

    My  grandfather  died  last  year.  When  everyone  was  crying  to 4 goodbye  to  him,  my  mom  asked  me the 5again.

    I didn't understand her, so I asked her, “It is a game 6 you and me?” She looked into my eyes and told me, “You know, it shows how you live 7 life.” She said with tears, “My dear, the most important body part is your shoulder(肩膀).”

    I asked, “Is it because it holds up my 8 ?”

    She replied, “No, it is because it 9 hold the head of a friend or loved one. 10needs a shoulder to cry on.”

有人说，日本明治维新是自身条件尚未成熟、在外部因素催化下发生的资产阶级改革。这里的 “外部因素”主要是指(   )