morning ['mɔ:niŋ]
n.早晨;上午
class [klɑ:s]
n.同一个班的学生
on [ɔn]
prep.在;在...上
duty ['dju:ti]
n.职责;责任
on duty
值日
we [wi:;wi]
pron.我们
aren't [ɑ:nt]
=are not