valveless

例句：

1. 1.The car is valveless, so it doesn't need to be serviced regularly.
   这辆车是无阀的，所以不需要定期维护。
2. 2. The new pump is valveless, which saves a lot of time and effort.
   新的泵是无阀的，节省了大量的时间和努力。
3. 3. The valveless design makes the machine more efficient and reliable.
   无阀设计使机器更高效和可靠。