问题补充：
请根据划线部分提问Tim went to the mountains with his friends last week.划线部分是his friends
答案：
Whom did Tim went out with to the mountains last week?
======以下答案可供参考======
供参考答案1:
with whom did tom go to the mountain last week
或 whom did tom go to the mountain with last week
第二句中whom也可用who
供参考答案2:
Whom did Tim went out with to the mountains last week?
