在疾病流行过程中，具有明显连锁性，可追查到传染源的疾病是（）
A.狂犬病
B.犬瘟热
C.犬细小病毒
D.布鲁氏菌病
E.炭疽
参考答案：A
What is NOT a function of the steam drum of a marine water-tube boiler（）.
A.Receives saturated steam from the generating tubes
B.Serves as a reservoir of boiler feed water
C.Holds internal fittings for separation of moisture from steam
D.Collects steam exhausted from the turbines
天然金刚石钻头在塑性地层中，切削过程相当于“犁地”，称作（）。
