钩端螺旋体病的主要传染源是（）
A.猪、牛、马
B.猫、鼠、兔
C.鸡、鸭、鹅
D.犬、猫、羊
E.猪、鼠、犬
参考答案：E
―Hurry up! Alice and Sue are waiting for you at the school gate.
―Oh! I thought they ________ without me.
A．went
B．are going
C．have gone
D．had gone
简述机械排烟系统如何进行联动调试。
