e is usually hard for a single mother.对于单亲母亲来说,生活总是艰难的。Рsmooth [smuːð] adj. 顺利的;光滑的;平稳的РThe skin of the snake feels smooth and cool.蛇的表皮摸起来又滑又凉。РOur path in life will not always be smooth.我们的人生之路不会永远平坦。Рsocial['səʊʃ(ə)l] adj. 社会的,社交的РUnemployment and crime are social issues.失业和犯罪都属于社会问题。Рsoft[sɒft] adj. 软的,柔软的;温柔的РMany people prefer soft colours and soft music.很多人喜欢柔和的色彩和轻音乐。Рsolid['sɒlɪd]adj. 固体的;立体的;结实的 n. 固体;立方体РIs the baby eating solid food yet?宝宝开始吃固体食物了吗?РGold is a solid, but it es a liquid when you heat it.黄金是固体,可是它加热时就成了液体。Рsort[sɔːt] n. 种类;方式;品质v.挑拣; 分类(常与out, over连用)РI sorted the books into English ones and Chinese ones.我把这些书整理为英语和汉语的两类。РHe’s sort of person who never tell lies.他是那种不说话的人。Рsour [saʊə] adj. 酸的;发酵的РIf you leave milk in the sun, it goes sour quickly.如果把牛奶放在阳光下,它会很快变算。