A.to see
B.to have seen
C.seeing
D.seen
第1题:
They ______ loading at 1400 hours.
A.started
B.finished
C.completed
D.reported
第2题:
第3题:
第4题:
A vessel in distress should send by radio telephone the two tone alarm signal followed immediately by the ______.
A.distress position
B.spoken words “Mayday, Mayday, Mayday”
C.ship’s name
D.ship’s call letters
第5题:
第6题:
真核生物ITS序列由ITS1和ITS2两部分组成。