4km²=______m²

5200cm=______m

1L-130mL=______mL

6007kg=6t+______kg．

A wildcat ia a（）.

A.deeply-grooved drum on the windlass with sprockets with engage the links of the anchor chain

B.winch that running out of control due to a failure of the overspeed trips

C.line that has jumped off the gypsyhead while under strain

D.nylon line that parts under strain and whips back in a manner