____ the people have become masters of their country _____ science can really serve the people. [ ]

______ food is hard to find, few birds remain throughout the year.

You must go to the ________ if you want to buy vegetables.

依次填入下列各句横线处的成语，最恰当的一组是（ ）① ，重视纪律，是警察最重要的界线。但若打破警界线，勇探与悍匪合作，侦缉与破案能力可能变成无限大。②在我们社会主义社会里，是非、善恶、美丑的界限应 ，坚持什么、反对什么，倡导什么、抵制什么，必须旗帜鲜明。③ 的美国联邦众议院通过应急预算法案，让政府在新年度得以维持运作，但此法案也斩断了总统奥巴马医改法案财源。

_____ U2, the Irish rock band from Dublin perform a concert in Beijing, tell me in advance.