【单选题】Save your work often as a ____ against computer failure.
【单选题】电压幅值差引起的冲击电流主要为 。( )
【多选题】单缸四冲程内燃机机构是由()齿轮、凸轮、推杆等构件组成。
【简答题】单缸内燃机结构示意图中的曲柄滑块机构,由( )4、( )3、( )2 和( )1 构成,作用是将( )4 的往复移动转换为( )2 的连续转动。
【单选题】Save your work often as a___ against computer failure.
【单选题】You should save your work often as a()against computer failure.