A:found
B:founded
C:was founded
D:was founded
____ A.cow B. horse C. sheep D. animal
____ A. pig B. litter C. throw D. open
____ A. zoo B. farm C. great D. school
____ A. moo B. tiger C. quack D. neigh
____ A. duck B. cows C. horses D. pigs
如图所示,若绳及滑轮重不计,绳与滑轮的摩擦不计.已知用F=30N的拉力可使物体沿水平地面匀速运动,那么,下列所求物理量正确的是( )