butterfly drop的意思|示意

Play great positioning pin ensures disc not because butterfly plate gravity drop, also can be installed in the valve stem end adjustment block to ensure that the butterfly plate fixed position.

弹赞定位销可保证蝶板不会因为蝶板重力作用下坠，还可在下阀杆端部设置调整块来保证蝶板位置固定。

The findings showed that over 20 years there was a 71 percent drop in native butterfly populations and a 54 percent drop in bird populations.

结果发现，20年来本地蝴蝶的数量下降了71%、鸟的数量下降了54%。