【2013山东聊城】If you want to buy this dress , you 'd better ______ first to make sure it fits you .
Father won’t allow me to play outside ________ I wash up the dishes.
Scientists can look _______ the huge telescope to find the planet.
About _______ of students ______ reading stories in English in our class.
He watched TV for an hour. At 8 o’clock he stopped _______ his homework.
He didn’t go to bed _______ his mother came back.