sing的过去式和过去分式

　　Do sing along if you know the words.

　　要是知道歌词，你就跟着唱吧。

　　I'll sing if I want to ─ there's no law against it.

　　我想唱就唱——谁也管不着。

　　There is some similarity in the way they sing.

　　他们的演唱风格有点像。

　　I can't sing that high.

　　我唱不了那么高的调子。

　　He doesn't sing all that well.

　　他唱得并不特别好。