They have a line on our friend.

他们查到我们朋友了。

Maybe you had a line on some.

或许你手头有点。

I haven't bought it yet, but I have a line on it.

我还没买，但我有一条线在上面。

Besides, my friend from the subway has a line on some.

而且 我地铁上的朋友刚好有点货出手。

" I have a line on a good used car" means I know someone who is selling a used car.

“I have a line on a good used car”表示我认识一个卖二手车的人。