Rail cars are joined together with ________ .2、________ is joined using chains and hooks.3、The yard master asked the worker to ________ the incoming freight cars.4、A buckeye couple relies on ________ to latch cars together.5、Because the cars were joined by a ________ they could not be unlatched easily.第二组内容A、knucklesB、couplersC、bar couplerD、3-link couplingE、couple