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1·It's not easy to kill a full-grown tree - especially one like the pion pine.

要弄死一棵成年的树，尤其是像矮松这样的树并不容易。

2·Methods The clinical dats of 38 cases (42eyes)with anterior ischemic optic neuropthy (AION) and 3 cases (5 eyes) posterior ischemic optic neuropthy (PION) were retrospectively analyzed.

方法回顾分析了38例4 2 眼前部缺血性视神经病变（AION）及3例5 眼后部缺血性视神经病变（PION）的临床资料。

3·Dr Learned and Dr Zee have come up with a design for a particle accelerator that would do the job a good deal more modestly, using another type of subatomic particle, the pion, as an intermediary.

莱德和哲博士设计出一种粒子加速器，利用另一种亚原子粒子n介子作为中介，从而实现更优的方案。