at在什么时候用,造4个句子

at
介词 prep.
1.在...地点
They were already waiting at the gate when I got there.
当我到达那里时,他们已等候在门口了.
2.在...时刻
Jane will meet her boy friend at Christmas.
简将在圣诞节和她男友见面.
3.向,朝,对着
Don't shout at me.
别对我叫喊.
4.在...方面
He is an expert at troubleshooting.
他是位排解争端的能手.
5.因为,由于
I woke at the sound of the bell.
随着铃响,我醒了.
6.从事于,忙于
He is working hard at this thesis.
他正在努力地撰写论文.
7.以(某种价格、速度等)
They sold the cloth at a dollar a yard.
他们以每码一元的价格出售这种布.