某科学兴趣小组为了探究拔河比赛取胜的秘密实验，第1次（如图1），甲、乙两人站在地上分别用100牛的拉力，结果两人正好处于相持状态，则弹簧秤的读数为____牛；第2次（如图2），甲站在一平板小车上，乙站在地面上，两人仍用100牛顿的拉力拉绳，甲同学被乙同学匀速向右拉动，则此时弹簧秤的读数____（选填“大于”、“小于”或“等于”）100牛，（整个过程中不计绳及弹簧秤的自重）．

阅读文言文，回答问题

上书谏吴王（节选）

       夫十围之木，始生如蘖^①，足可搔而绝^②，手可擢而抓，据其未生，先其未形^③。磨砻砥砺^④，不见其损，有时而尽。种树畜养^⑤，不见其益，有时而大。积德累行不知其善有时而用弃义背理不知其恶有时而亡。臣原大王熟计^⑥而身行之，此百世不易之道也。

     【注释】①蘖（niè）：植物的幼芽。②足可搔而绝：用脚可以踩断。③据其未生，先其未形：在它未成长之前（就抑止它），在它未形成之前（就抑止它）。④磨砻砥砺：四种磨刀工具。⑤种树畜养：种植物，养牲畜。⑥熟计：仔细考虑。

南北回归线均穿过的大洲是（    ）

    Mary is an African elephant. Now she is 16 years old.She lives in the zoo. Mary has produced more than 50 drawings since last year. She has made over $2,500 for the zoo. Zoo leaders said Mary first showed the art ability (能力) about 4 years ago. Zoo workers watched her make the marks (痕迹) in the sand with her trunk (象鼻). She rubbed out (抹去) the marks, then made the new ones. The zoo workers gave her brushes and paints. Soon Mary was drawing pictures. Newspaper reporters wrote about Mary, and then people went to buy her pictures. And in this way she made a lot of money for the zoo by drawing.

    This is how Mary does the drawing.A zoo worker holds different color paints and Mary touches the colors she wants. Then the worker gives her chosen color to the brushes in her trunk and Mary begins to paint.

 盐酸和氯化钡的混合溶液40g，其中盐酸的溶质质量分数为10%．向混合溶液中加入9%的硫酸溶液20g恰好完全反应．计算：