从生物材料中提取天然大分子药物时，常采用的措施有采用（）、（）、抑制水解酶作用等
参考答案：缓冲系统；添加保护剂
Thinking that the students were having an evening class, the teacher left the classroom, ______.
A．slowly and gentle
B．slowly and gently
C．slow and gentle
D．slow and gently
预防佝偻病应强调（）
A.母乳喂养
B.及早添加辅食
C.及早口服鱼肝油
D.及早服用钙剂
E.经常晒太阳
