慢性支气管炎并发肺气肿的主要症状为()
A.突然出现呼吸困难
B.逐渐加重的呼吸困难
C.窒息
D.发绀
E.心悸
参考答案:B
用所给词的正确形式填空。
1. "Do you like noodles?" "No, I don’t like _____ at all."( they )
2. He often _____ letters to his mother. ( write )
3. Our _____ begin at 7:30 every morning. ( class )
4. We are twins. I have long hair, and she _____ long hair, too. ( have )
5. The _____ like milk and cakes. (baby)
实验动物按遗传学分类为()
A、相同基因类型、不同基因类型、中间基因类型动物
B、近交系、封闭群、杂交群
C、同源突变系、同源导入系、分离近交系、重组近交系
D、遗传限定动物、免疫缺陷动物、转基因动物