He____ find his____.
从方框中选择适当的短语,并用其正确形式填空。
catch up, nothing serious, feel a bit cold, get a fever, wait a minute
在梯形ABCD中,AD∥BC,对角线AC⊥BD,且AC=12,BD=9,则梯形两腰中点的连线EF的长是( )