乙型肝炎病毒的抵抗力很强,哪种方法可使其灭活()
A.乙醇消毒
B.居室通风
C.肥皂水洗涤
D.2%的来苏水浸泡
E.煮沸15分钟
参考答案:E
After he retired from office, Rogers ______ painting for a while, but soon lost interest.
A.took up
B.saved up
C.kept up
D.drew up
试述齿轮的点蚀现象。