When I come in,Xiaoyong was flying a kite.

come改came
祝你好运！

When i came in ,xiaoyong was flying a kite.当我进来时，小勇正在放风筝。

come---------came

was-->is

句子前面的动词是现在时，后面也是现在时，改成was-is;或者是come改成came,句子前后时态一致。