in the sun 在阳光下

[例句] The ice is melting in the sun.

冰在太阳’下融化。

[例句] The wet clothes will soon dry in the sun.

湿衣服放在太阳下面很快就会晒干。

under the sun 地球上，全世界

[例句] This is the best product under the sun.

这是人世间最好的产品了。

[例句]l can teach you everything under the sun.

我能教你天底下的任何事情。