The past tense of grin like a Cheshire cat is grinned like a Cheshire cat.
The third-person singular simple present indicative form of grin like a Cheshire cat is grins like a Cheshire cat.
The present participle of grin like a Cheshire cat is grinning like a Cheshire cat.
The past participle of grin like a Cheshire cat is grinned like a Cheshire cat.
