A door; esp. One of a pair of folding doors.

门(尤指双摺门之一)。

Any of various mechanical devices for opening and closing a conduit, and thus regulating or directing the movement through it of a gas, liquid, etc.

【机】活门；活瓣。

A fold in the wall of a blood vessel, or other organ, which allows the contents to flow though it in one direction only.

【解】瓣膜。

Either of the two separable pieces, as of the shell of a clam, the seed pod of the pea, etc.

贝壳；(果荚的)瓣。

Vacuum tube.

【英】真空管。

Device in certain wind instruments which, when depressed, changes the pitch of a tone.

管乐器的栓塞。