京张铁路修筑时，詹天佑面临着哪些困难( )。
①清廷拨款有限，资金不足 ②时间紧迫 ③沿线重峦叠障，修路工具简陋
④外国人的嘲笑
A：①②③
B：①②③④
C：②③④
D：①②④
— What do you think of your teacher?
— He is very kind. He always the students his own children.
下列河流有“一江连多国，东方多瑙河”之称的是（ ）
