The flowers his friends gave him will dieif _______ every day

依次填入下列各句横线处的成语，最恰当的一组是（ ）①_______________，有言必践，传送着中国的极大诚意，展示了一个负责任大国的襟怀，赢得了世贸成员和国际舆论的佳评。②出了事故，首先应调查原因。“没有调查就没有发言权”，这是决策的科学化问题。古今之市领导，似乎还在车上，就作出重大决定了。而且_______________，权重如天。③在推销的过程中，应该认真准备，力求表达得精炼准确，_______________ ，以达到最佳效果。

If _____ for an explanation for an advanced camera, I would certainly find it difficult.

Could I borrow your camera— __________, but please give it back before Saturday.

Scientists have been the temperature of the oceans to see how it changes over a period of time.