On Sundays there were a lot of children playing in the park, ________ parents seated together joking．

A．their

B．whose

C．which

D．that

启动起网机要平稳，挂好油泵皮带再接离合器，将分配阀（也叫换向阀）置于空车挡，要准确讲手柄推向相应挡位。