Left middle finger: engagement.

左手中指：订婚。

youdao

The polling officer didn't even raise her head. After dipping a plastic straw into a bottle of purple ink, she drew a blotchy line down the middle finger of my left hand.

选举官头也不抬，用塑料棒沾了紫色墨水就在我左手的中指上抹下一条污渍。

youdao

One index finger to control the left mouse button, middle finger to control the right mouse button.

其中食指控制鼠标左键，中指控制鼠标右键。

youdao

Szczesny has missed four matches since damaging the middle finger on his left hand but was given the all-clear following a scan last week.

BBC: Wojciech Szczesny

If off-spinner Hauritz is ruled out after being hit on the middle finger of his right hand during the team's final practice session, left-arm fast bowler Mitchell Johnson will be the only member of their attack to play in all three Tests.

BBC: Paceman Clint McKay to make Test debut for Australia