当一只苍蝇突然飞临你的眼前时,你会马上眨眼睛。这种现象叫 [ ]
A.感觉
B.刺激
C.反射
D.感知
答案:C
已知点P(x0,y0)、直线l:x0x+y0y=r2和⊙O:x2+y2=r2,且点P在⊙O内,则直线l与⊙O的位置关系为( )
A.相切
B.相离
C.相交
D.不能确定
All the holds which are to take cereals in bags must be so cleaned that thay meet the requirements of the().
A.local agent
B.crgo surveyor
C.accident investigator
D.general average adjuster