advance base camp的用法和样例：
- "They could see Chinese soldiers quite close to Advance Base Camp kneeling, taking aim and shooting, again and again, at the group, who were completely defenceless," he said.
- A base camp for the mountain climbers.
- On May 4,they safely backed to the base camp.
- They set out on their return to the base camp.
- All climbers are now safely back at base camp.