31) The dancers stood ..... a circle before starting the dance.
Explanation: 'in' is used to indicate a shape
32) You must not swim ...... this canal here.
Explanation: The preposition 'across' is used to show movement from one side to another side
33) They were dancing ....... the campfire.
Explanation: preposition 'around' is used to show a circular way
34) The dog jumped .... the roof.
Explanation: preposition 'onto' shows movement to a place
35) She likes going ..... Australia in summer vacations.
Explanation: 'to' shows towards