结肠癌在我国的发病率有增高的趋势，发病原因与遗传、少纤维、高脂肪饮食习惯等有一定关系．下图表示结肠癌的发病机理，请回答以下问题．

（1）结肠癌症发生的根本原因是____，并不断积累，主要是由____ 、____ 两方面原因导致的．

（2）科学家近年来发现体内的一种物质IL﹣17对于结肠癌形成有重要影响．IL﹣17是由某种效应T细胞（Th17）分泌的一种____ （免疫活性物质）．当把结肠癌细胞移植到进行了IL﹣17基因敲除（特定基因在胚胎发生早期被灭活）的小鼠体内后，肿瘤体积和肿瘤细胞数目远远高于对照组，说明IL﹣17对结肠癌的形成有____ 作用．

（3）结肠癌组织可分泌表达一种特殊的糖蛋白，它作为____ 可引起患者的免疫反应．为了检测体内是否存在癌细胞，可以采用____ 技术，该技术需要用到细胞工程生产的____ ．

（4）家族性结肠息肉病是一种常染色体显性遗传病，如不治疗，10岁以后患结肠癌的可能性较大．该病主要由APC基因突变导致．为治疗该病，科学家曾尝试将正常APC基因用脂质体（一种人工磷脂双分子层膜）包裹后，使其进入体外培养的活体小肠系膜细胞中，再将转基因表达成功的细胞导入病人体内．脂质体在此过程中相当于基因工程中的____．上述治疗方法被称作____ ．

根据短文理解，从A、B、C、D四个选项中选择最佳答案填空。

    Many scientists say that the world is getting hotter and hotter. If they are right, the ice at the North and South Pole will melt eventually. If this happens, the sea will 1 and may cover most or all of Singapore. This will force everybody to move to a 2 country.

    We know that the sun 3 the earth. The heat from the sun hits the ground, and some of it goes back into the sky. However, factories and cars 4 a lot of carbon dioxide (二氧化碳). When the gas rises into the sky, the heat from the sun can come through them but the heat from the ground cannot. It 5 near us in the sky and makes the 6 hotter and hotter every year.

    Scientists 7 this the “greenhouse effect” because a greenhouse is a small glass building which is hot inside. It is used for     8 plants in cool countries. Many countries are 9 about the “greenhouse effect”. They are trying to stop factories and cars from sending  10 gases into the sky. Scientists are not sure when the world will get much hotter. Some people say that the “greenhouse effect" has started already and has begun to affect (影响) the world's weather.

撒哈拉以南非洲的主要人种是（   ）