单项选择题
A.danger B.dangerous C.A+B D.A or B
（）social instruction on cargo securing.A.HasB.HadC.Have...
单项选择题（）social instruction on cargo securing.
A.Has B.Had C.Have D.Having
Go （）this ladder and walk aft.A.downB.toC.upD.in
单项选择题Go （）this ladder and walk aft.
A.down B.to C.up D.in
The first cabin astern of the saloon is（）.A.heB.himC.hi...
单项选择题The first cabin astern of the saloon is（）.
A.he B.him C.his D.they
