The hall had no spare seats left last night ________，the performance achieved a great success [ ]

They will start their project, ________at helping the poor children to be educated in the west of China. [ ]

Please don’t talk loudly ! The baby is sleeping! —-Sorry. ______

It’s helpful to put students in a situation _______ they can learn how to cooperate with each other.

下列各句中，划横线的成语使用恰当的一项是（ ）