单项选择题 Some people are against killing wolves because ． A．wolves help to keep the ecological balance in the wildemessB．there is too small a wolf population in the wilderness C．there are too many deer in the wildernessD．wolves are afraid of people and never attack people

单项选择题 According to those against killing wolves，when wolves eat other animals， ． A．they never eat strong and healthy ones B．they always go against the law of nature C．they might help this kind of animals survive in nature D．they disturb the ecological balance in the wilderness

单项选择题 对有机含量较多的土、硫酸盐含量（）的土及重黏土，不宜用水泥来稳定。