at ease ---------free from nervousness 不紧张地 ------- comfortable ,comfort ---so easy !
off balance失去平衡的= unsteady
single out 选出,挑出
nuclear 核能的 physics------applied physics
compete竞争------competition ------- competitor竞争者
survive-------survivor幸存者 disaster灾难 earthquake地震 flood洪水,水灾 drought旱灾 traffic accident ------ drown 淹死 poison毒药 poisonous有毒的 poisoning中毒