对号入座（介词填空。）

（1）He’s showing his stamps _____ his friend.
（2）Stand ___ a line.
（3）Jump up and __________
（4）Lift___ your legs.
（5）Lie____ your back.
（6）We go to school _____seven ___ the morning.
（7）My mother washes clothes ______ Sundays.
（8）I clean the photos ______ supper.
（9）They’re _____ the plaground.