Do you like this puzzle?（由this可知是单数）
There is some juice in the bottle.(juice不可数,故用is)
The mouse is in the cat's mouth.（由句意可知老鼠在猫嘴里,故用属格）
Look at his toy bear.（由句意推断可知是属格,用his）
There aren't any pianos in the sports hall.（由aren't可知应用复数,piano复数加s）
My sister is a waitress.（由sister可知是女性职业,用waitress）