霍乱的治疗过程中首选的抗生素为（）
A.氯霉素
B.多西环素
C.四环素
D.氨苄西林
E.卡那霉素
参考答案：B
Easter Island, which was almost uninhabited when it was discovered on Easter Day in 1722 by a Dutch captain, is covered with hundreds of giant statues, each _______ several tons.
A．weighing
B．weighs
C．weighed
D．to weigh
数显仪检定周期是多久？
