小白鼠是细菌学研究常用实验动物,其优点是()
A.对传染病抵抗力强
B.易于饲养管理
C.对多种细菌有易感性
D.品系较多
E.耐饥饿,耐寒冷
参考答案:B, C, D
Thank you for all your hard work last week. I don't think we ______ it without you.[ ]
A. can manage
B. could have managed
C. could manage
D. can have managed
铸造全冠试戴时,固位差的原因,不正确的是()。
A.未完全就位
B.龈距短
C.聚合度大
D.代型上的间隙剂过厚
E.石膏代型磨损