帮助某人做作业用英语可以说：

1. Help sb. with his homework

2. Help me do the homework

3. Help me to do the homework

4. Help me with my homework

5. Could you please help me do my homework

建议根据具体的语境选择合适的表达方式。例如，在正式场合或需要表达礼貌时，可以使用“Could you please”来提问。