The first sensor monitors the camshaft position delivering one pulse per revolution which corresponds to the top-dead-centre (TDC) position of one of the pistons.
第一个传感器用来监视每次旋转时释放一次脉冲的机轴位置，该位置相当于某一活塞上止点的位置。
2
Mars was visible, dead in the centre of the telescope.
火星清晰可辨，正好就在望远镜的中心。
《柯林斯英汉双解大词典》
3
Thousands of innocents lie dead in the wreckage of the World Trade Centre; hundreds more seem likely to have perished at the Pentagon and in a crashed airliner in Pennsylvania.