There was nothing to fall back on so valvular surgery without an artificial valve - at least as a backup - was a very dangerous game to play.

所以，没有人造瓣膜的瓣膜手术是一个非常危险的游戏。

youdao

Neoprene tube cover, plug-n-play reservoir attachment, bite valve with cover.

氯丁橡胶管套，即插即用存储附件，咬阀盖。

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Suggested opening the user can freely adjust the size, the appropriate valve size increases, and thus play a role in reducing the wear and tear.

提议用户在可以开度自在调节的规模内，适当增大阀门的口径，从而起到减小磨损的作用。

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The entire title is now free-to-play, with Valve only making money from microtransactions within the game.

FORBES: Valve's Team Fortress 2 Goes Free to Play

TF2 was where Valve first introduced free-to-play, as well as microtransactions with its hat system (among many other initiatives).

ENGADGET: Valve's Joe Ludwig on the uncertain future of virtual reality and partnering with Oculus

With any luck, that input will start rolling in soon: Valve is preparing to update its popular free-to-play shooter, Team Fortress 2 with a Rift-compatible VR mode, openly describing the update as an experiment.

ENGADGET: Oculus' Palmer Luckey and Nate Mitchell on the past, present and future of the Rift