根据伤亡事故处理规定,伤亡事故处理工作应当在( )日结案。
A.70
B.80
C.90
D.100
参考答案:C
电子显微镜下观察到的烟草花叶病毒的形状是( )
A.球形
B.螺旋形
C.杆形
D.蝌蚪形
You have spoken very good English , _____ you're the beginner of learning. [ ]
A. after all
B. for example
C. to speak the truth
D. for instance