若管道腐蚀程度严重,应尽快降压和维修,则管体腐蚀损伤评定类别为()。
A.2
B.3
C.4
D.5
参考答案:C
根据句意,用括号内所给单词的适当形式填空。
小题1:Li Hua likes playing football and he plays football _________ (good).
小题2:Koby and Iverson are my __________ (hero).
小题3:Sandy goes __________ (swim) three times a week.
小题4:The watches on the table are those football __________ (play).
小题5:I __________ (real) enjoy the stories he tells me.
如图所示,在倾角为300的粗糙斜面上有一重为G的物体,若用与斜面底边平行的恒力F=G2推它,恰好能使它做匀速直线运动.物体与斜面之间的动摩擦因数为( )
A.22
B.33
C.63
D.66