他无法掩饰脸上洋溢的欣喜笑容。

He couldn't hide the delighted ___grin that spread across his face.

他们灿烂的笑容充分说明了他们的兴奋。

Their broad ___grins spoke volumes about their excitement.

他们之间交换了一个会意的笑容，心照不宣。

A knowing ___grin passed between them, acknowledging the shared secret.