let out
放出,释放（水、空气等）；呼（气）
It lets sunlight in but doesn't let heat out...
它吸收阳光,但并不释放热量.
Meer let out his breath in a long sigh.
米尔长叹了一口气.
发出（声音）
When she saw him,she let out a cry of horror.
她看见他时吓得大叫一声.