该图是春分日正午垂直立在北半球不同纬度四个地点的四根长竹竿影子的长短情况，四地纬度由高到低排列正确的是（   ）

A．①②③④

B．④③②①

C．①④③②

D．②③④①

Premier Wen Jiabao said that if we worked hard and ________ optimistic, we were ________ win the

war against the swine flu.[ ]

A．were; bounding  

B．were; bound to

C．was; bounding to  

D．had; bounded to