perk up

动词 perk up:

1. gain or regain energy
   同义词：perk, percolate, pick up, gain vigor
2. cause to be alert and energetic
   同义词：stimulate, arouse, brace, energize, energise

1. He looked depressed but perked up when his friends arrived.
   他看上去无精打彩的，但朋友一来就精神起来了。
2. The horse perked up its head when I shouted.
   我吆喝时那马扬起了头。