【简答题】蛙泳完整配合技术中,练习者出现“吸不到气”的错误动作该如何纠正?
【单选题】以下( )不属于数据库系统中数据的特点。
【单选题】The bearing cap and shell are replaced and tightened up until ______.
D.
the “ clearance ” is correct
【单选题】The bearing shell generally has _____ for location and oil grooves round the center of its axial length.