Backrest should not be too inclined, and should be vertical, and the cushion is roughly when drivers are back roughly parallel to the back of a chair.

座椅靠背不应太斜，而应与坐垫大致垂直，驾驶人正坐时，后背大体与靠背平行。

youdao

Drivers have to jump off a chair onto the injured leg and suffer no undue reaction to prove that they can withstand the rigours of a long race.

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