单项选择题
A.which B.what C.how D.when
Be careful when you （）the derrick.A.operatedB.operateC....
单项选择题Be careful when you （）the derrick.
A.operated B.operate C.operating D.operator
Is that all right at this（）?A.highB.heighC.heightD.high...
单项选择题Is that all right at this（）?
A.high B.heigh C.height D.higher
What’s the （）of the derrick?A.SLWB.LSWC.SWLD.FWE
单项选择题What’s the （）of the derrick?
A.SLW B.LSW C.SWL D.FWE
