根据短文内容，选择正确答案。

    I am a student in China now. My name is Kelly Smith. I live with my parents, two sisters and a brother in Beijing. My parents teach English in No. 6 Middle School. I study in the same school. I am happy here, because I like my new school and the classmates. They are very kind to me. They like to play with me because I look different from them. I have blue eyes and long blond hair. They often say I look like a doll. Also I speak English well. so lots of students like to tam with me to improve (提高) their English.

比银河系高一级的天体系统是（　　）

一个四位数，347□，要使它能被2整除，□里可能是____

下列有关基因工程技术的原理或实质的叙述，合理的有(　 　)
①基因诊断的基本原理是DNA分子杂交；
②基因治疗的原理是将正常基因导入病人体内，使该基因的表达产物发挥功能；
③DNA探针技术的原理是探针与样品中变性处理的DNA单链配对杂交；
④构建基因表达载体的实质是基因突变；
⑤PCR技术的实质是体外复制特定DNA片段的核酸合成技术