我买了一部新手机，但它有点问题。

I bought a new phone, but ___it has some issues.

今天散步感觉很舒服。

___It feels nice to go for a walk today.

是我把钥匙忘在桌子上了。

___It was me who left the keys on the table.

那只小猫一直在叫，它可能饿了。

The kitten keeps meowing; ___it might be hungry.