Dad is dismounting the bike from its stand.

### 解释 dismounting 是动词 dismount 的现在分词形式。dismount 由前缀 dis-（表示"离开、去除"）和 mount（"安装、骑上"）组成，字面意思是"从...上下来"或"卸下"。 dismounting the bike 指"从自行车上下来"或"把自行车从支架上取下"的动作。