美元硬币在美国一直不太流行。

The dollar ___coin has never been very popular in the United States.

我祖父收藏来自世界各地的古币。

My grandfather collects old ___coins from around the world.

今天在人行道上发现了一枚闪闪发亮的硬币。

I found a shiny ___coin on the sidewalk today.