A.once B.twice C.three times D.four times

医疗器械注册证格式为“国械注××××××××&

How many generators does the shuttle carry？A．One.B．Two.C．Three.D．Four.

How many times had the author failed before she was able to send away all the pups？A．Once.

A．One group of pictures.B．Two groups of pictures.C．Three groups of pictures.D．Four groups

How often is the release？A.Once a month.B.Twice a year.C.Once a year.D.Every two or thr

A．One.B．Two.C．Three.D．Four.