2013年，我国中央政府适度增加财政赤字和国债规模，继续完善税制改革和结构性减税，在环保、社保卫生、三农、科技教育方面加大支出，进一步改善民生。下列对这一政策认识正确的是（    ）

①发行国债有利于弥补国家财政赤字，支持重点工程建设

②保持适度的财政赤字和国债规模属于适度宽松的货币政策

③保持适度的财政赤字和国债规模属于适度从紧的财政政策

④保持适度的财政赤字和国债规模属于积极的财政政策

某实验小组的同学用氢氧化钙溶液和盐酸进行酸碱中和反应的实验时，向烧杯中的氢氧化钙溶液加入稀盐酸一会后，发现忘记了滴加指示剂．因此，他们停止滴加稀盐酸，并对烧杯内溶液中的溶质成分进行探究．

增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：1）每处错误及其修改均仅限一词;

2）只允许修改10处，多者（从第11处起）不计分。

    As we all know, we can meet with various challenges in our life. Faced with challenges, how should we do?

    Last month, our class climbed Mount Tai, that is more than 1,500 meters above sea level. Lacking exercise, I thought that this activity was great challenge for me. I felt very exhausted halfway that I wanted to give up. See this, my classmates and even some strangers encourage me. By the end, I managed to reach on the top of the mountain.

    Therefore, don't give up in face of challenges. If you are determined enough, it's certainly that you can overcome it.