九、 完成句子(5小题, 每小题1分, 计5分):根据汉语提示，将英语句子补充完整。
76.这张桌子太重我搬不动。
The desk is _________ _________ for me _________ _________ .
77.他们昨天在晚会上玩得很开心。
They _________ _________ _________ _________ at the party yesterday.
78.莫扎特4岁时开始写曲子。
Mozart started _________ _________ when he was four years old.
79.当我出去的时候我看见他们在踢足球。
I _________ _________ _________ football when I went out.
80.The boy began to go to school _________ _________ _________ _________ .(在.他7岁时)
，我们将会及时处理。
