A.How longB.How lengthC.How many timesD.How many shift（……

单项选择题（）will reduce the visibility.

A.dust
B.sea water
C.land sand
D.wind

单项选择题（）view of the fact，I wish to submit this report.

A.In
B.On
C.To
D.For

单项选择题（）using the derrick at once，the gooseneck is bent.

A.Continue
B.Start
C.Commence
D.Stop

单项选择题（）this the Chief Officer agreed not to put any remarks.

A.At
B.By
C.For
D.Upon

单项选择题（）there danger of explosion?

A.Is
B.Has
C.If
D.Do