If parents treat their children with love and affection, teenagers will flourish like flowers in the sunshine.

flourish 是动词，原意是"茂盛、繁荣"，用来形容植物生长旺盛的状态。这个词常用来比喻人或事物蓬勃发展、茁壮成长的状态，就像花朵在阳光下绽放一样。