Oxygen is often stored as a liquid although it is used () as a gas.A primarilyB seldomC

A reservoir, as used in hydraulic systems aboard ship, is used to store hydraulic oilAnoth

Cylinder liner cooling is often referred to as _____.A.piston coolingB.sleeve coolingC.cen

Which of the following italicized parts is used as an object complement？A．He is often hear

Which of the following reflexive pronouns（反身代词)is used as an object？A．John often put h

In China, modesty is often regarded as a traditional virtue. But sometimes, especially in

A red light is often used as a danger _____.A. signalB. signC. warningD. reminder