5. I am listening to someone singing.
我在聽人唱歌。
還能這樣說：
Listen, there is someone singing.
I hear someone singing.
諺語：
When the owl sings, the nightingale will hold her peace.
梟鳥唱歌，夜鶯屏息。
6. The singer was singing to the guitar.
那個歌手正和著吉他唱歌。
還能這樣說：
The singer sang while playing the guitar.
The singer was singing with guitar accompaniment.
諺語：
The swan sings when death comes.
死期來到，天鵝歌聲美妙。
7. If there is time I will sing all the songs that I learned.
如果還有時間的話我會把我所有會的歌都唱一遍。
還能這樣說：
If time permits, I wish I could sing all the songs that I learned.
With enough time, I will sing all my learned songs.
應用解析：
ahead of the times 跑在時代前頭；
ahead of time 提前；
at a time 一次；同時；
at times 有時，偶爾；
behind time 誤時
8. My singing is out of tune.
我唱歌跑調兒了。
還能這樣說：
I sing out of tune.
I sing off key.
諺語：
There's many a good tune played on an old fiddle.
老當益壯。