阅读下列材料，回答问题：

材料一    尽管遭到美国和欧洲的强烈反对，但俄罗斯武装力量仍果断进驻克里米亚多处战略要地。2014年2月28日以来，驻扎在塞瓦斯托波尔的俄黑海舰队率先行动，随后俄军从海空同时大举增援。正如路透社所言，与160年前同英法冲突时色厉内荏的俄国相比，经过精心准备的俄军面对西方压力时，己表现得底气十足，毫不示弱。

——《环球时报》（2014年3月3日）

材料二    下列是一组与1861年俄国农奴制改革相关的文字和图片：

下图描绘了被地主宣布“解放”的农民伏在地上亲吻主人脚面的情景

②一个目击者回忆农民听取“解放”法令的反应时说，“农民们愁容满面并且低下了头……农民中怨声和叫喊越来越高……”。

③1876年，一位地主说：“解放法令颁布十五个月后，当我再看到农民时……受奴役的所有迹象都已经消失的无影无踪。”

材料三  历史学家爱德华·拉津斯基这样写道：“对俄国来说，亚历山大二世属于一种新型的改革者，他像是两面神亚奴斯，一张脸孔望着未来，一张脸孔望着过去……”

请回答：

    Why do I volunteer with Big Brothers Big Sisters of America? I have many reasons. Perhaps the biggest reason is that someone volunteered to help me. Years ago, I was on the other side of the table. I was lonely and felt kind of lost. More than once, I found myself on the wrong side of a jail cell(牢房). If someone hadn't stepped in, I probably wouldn't even be here right now.

    I've seen the work that Big Brothers Big Sisters has been doing all over the country and I'm pleased to be part of it. I've never done anything that made me prouder than my volunteering work. Big Brothers Big Sisters helped me get my head on straight. There are no words to describe the joy I get from helping somebody turn their life around.

    Don't tell anyone I said that, but volunteering is probably the fastest way to get over sadness or depression. Every time I start to feel bad, I talk to someone who needs my help and it makes me feel better and worse all at the same time. I feel better, because doing good things fills me with a sense of pride. I feel worse because I feel I have no right to complain about my situation especially when I hear what others are going through.

    I've come a long way from where I was. Volunteering is how I want to leave my mark on the world. I recommend volunteering work to everybody, especially for somebody who isn't sure where they're going in life. Helping someone find their path is often the best way to find yours.

小明和小方分别向氢氧化钠溶液中滴加稀硫酸做中和反应时忘记使用指示剂，为了探究硫酸与氢氧化钠是否恰好完全反应．