dog's ear like skin fold

例句：

1. 1. The dog's ears twitched as itheard the sound of a car approaching.
   当狗听到汽车的声音时，它的耳朵开始抖动。
2. 2. Thedog's ears perkedup when he heard the doorbellring.
   当他听到门铃响时，狗的耳朵竖起来了。
3. 3. Thedog's ears twitched in fear as itsaw a stranger approaching.
   当狗看到陌生人走近时，它的耳朵开始颤抖。