圣彼得堡是俄罗斯第二大城市。

St Petersburg is Russia's ___second biggest city.

伊拉克的石油储量仅次于沙特阿拉伯。

Iraq's oil reserves are ___second only to Saudi Arabia's.

这些囚犯的关押条件是最好的。

The conditions that these prisoners are kept in are ___second to none.