dead point的用法和样例：
例句
- These gateways provide a choke point at which security and auditing can be imposed.
这些关卡提供了一个扼止点，在此可以进行安全检查和审计。 - The spark is therefore timed to occur before the piston reaches top dead center, otherwise maximum pressure would not be reached in time.
因而，在活塞到达上死点前，火花便会发生，否则就不可能适时达到最高的压力。
