Have a field day:

過著田野的日子 ×

特別痛快，特別過癮 √

例句：

We had a field day at the amusement park.

全家老小在游樂場(chǎng)里玩得十分盡興。

To give one's best shot:

發(fā)揮出某人最好的水平

例句：

He will give it his best shot in the match.

他會(huì)在比賽中努力發(fā)揮出自己最好的水平。

For a song:

為了一首歌 ×

買了便宜貨 √

例句：

You picked it up for a song.

你真是買到便宜貨。