He_____ is lost. [ ]
A. may
B. maybe
C. may be
D. can
B
反密码子UAG识别的mRNA上的密码子是()
A.ATC
B.AUC
C.CTA
D.CUA
E.GTC
L≥50m船舶的桅灯最小能见距离为:().
A.5海里
B.3海里
C.6海里
D.1海里