--Would you like to ride bicycles with us tomorrow?--Yes I’ll go I’m free.A.becauseB. when

问题补充：

--Would you like to ride bicycles with us tomorrow?

--Yes,I’ll go I’m free.

A.becauseB. whenC. if

答案：

解析：A.because因为B. when当…时候C. if加入；句意：明天你想和我们去骑行吗？是的，如果我有空的话，我就去。故选C