the endless ____u_____and ____d_____ of living无尽的人生起伏
social relationships also ___d______(巨大而突然的,急剧的)influence our ___m______ rate社会关系也极大地影响着我们的死亡率。
we _____e______a spontaneous social _____i______ to make friends from a very early age.我们在很小的时候就表现出一种自发的社交本能,喜欢交朋友。
Through shared activities, strong ____b____(复数)are often created.通过共同的活动,往往可以建立牢固的纽带。