You _________ sleeping on the train.[ ]
A. was
B. were
C. is
答案：B
下列疾病不属于慢性病流行病学研究范围的是（）
A.血吸虫病
B.精神病
C.肿瘤
D.糖尿病
E.心血管病
Fuel oil tank vents are fitted with a screen which will stop（）.
A.oil from flowing out of the tank vent
B.air from entering the tank vent
C.vapors from leaving the tank vent
D.flames on deck from entering the tank vent
