B细胞表面最重要的协同刺激分子是

A．CD₂₀
B．CD₁₉
C．CD₃₅
D．CD₄₀
E．CD₈₀

In securing a towing cable，consideration must be given to letting go in an emergency. The possible whip of towlines when released can be overcome by（）.

A.increasing the shaft RPM prior to release

B.using a pelican hook for quick release

C.using preventers

D.using a short chain for the lead through the stern chock