a hour 还是 an hour?
a hour 还是 an hour?
a hour 还是 an hour
a half hour还是half an hour?
a one -hour还是an one-hour
an hour and half还是an hour and a half
冠词 an one-hour 还是a one-hour
是a one-hour ducumentary还是an one-hour documentary
hour前用a还是用an
hour前面加an还是a
是half hour还是half an hour?
half an hour or a half hour?
an hour one hour