The loss of the diesel engine cylinder air charge through leaky valves, piston rings, worn or scored liners, would be indicated by which of the following sets of conditions?（）

If ignited，which material would be a class B fire?（）

Which of the processes listed consumes the greatest amount of power while producing the greatest amount of heat?（）

不符合“A”型船舶特点的其他船舶均称为“B”型船舶。

Which of the listed materials would be considered as a bunting class "C" fire?（）

If ignited, which of the listed materials would be a class "B" fire?（）

（）means the sufficiency of a vessel in materials，construction，equipment，crew，and outfit for the trade or service in which it is employed.

Which of the listed effects represents the purpose of heat treating steel?（）

Which of the listed devices would be installed at a control system air pressure reducing station?（）

In which of the listed refrigeration system components does superheating of the refrigerant take place?（）

Which of the petroleum products listed has the lowest flash point?（）

A公司与B公司签订《船舶转让协议》，约定A公司将船舶转让给B公司，转让价格为XX万元B公司交押金X万元，以后每月支付船价及利息X万元，如两个月内不付转让费，A公司有权收回船舶由B公司负责办理船舶营运手续B公司中途无故退回船舶，已付的转让费不再退回，等等。B公司经营船舶一年后，以A公司提供的船舶陈旧，操纵性能差等为由，向A公司提出终止船舶转让协议。A公司欲协商，但协商不成，A公司收回船舶国籍证书，船舶技术证书及营运证书。该协议属海商法范围内的何种合同？该协议是否有效