咖啡馆门口挂着一个写着"营业中"的牌子。

There's a ___sign that says "Open" hanging outside the coffee shop.

请在表格底部签名确认。

Please ___sign at the bottom of the form to confirm.

落叶是秋天来临的迹象。

Falling leaves are a ___sign that autumn is coming.

老师正在用手语向学生们表达这些单词。

The teacher is ___signing the words to the students in sign language.