单项选择题()是安装在轴承上有一个或多个用于缠绕钢丝绳的轮槽的轮子。( A、绳轮 B、随行电缆 C、厅门上下行指示 D、梯级
多项选择题There are two types of clauses, which are ______________. A、endocentric B、exocentric C、finite D、non-finite
