sinificant adj.有意义的；重要的，重大的
Proper exercise plays a significant role in the rehabilitation of patients with various back ailments.对于各种背部疾病的患者来说，适当的锻炼对于康复有着至关重要的作用。
similar adj.相似的，类似的
I bought some new shoes which are very similar to a pair I had had before.我买了几双新鞋，与我之前的一双鞋非常类似。
simplify vt.单一化，简单化
The collegesimplified its complex entry requirements.学院简化广复杂的入学要求。
sincere adj.诚挚的，真诚的
He offered a sincere apology for his behavior.他为自己的行为表达了诚挚的歉意。
single adj.单一的；单身的
The sisters share one room with two single beds in it.俩姐妹共用一个放着两张单人床的房间。
singular adj.①单数的②显著的，非凡的
The singular form of “children” is “child”.“children” 的单数形式是“child”。
John developed a singular manner for dealing with angry people tactfully.约翰想出来一种巧妙应对生气的人的奇妙方法。
sink v.沉下，（使）下沉 n.水槽，水池
The storm sank two fishing boats.暴风雨造成两艘渔船沉没。
Davids dirty dishes piled up in the kitchen sink.戴维的脏盘子都堆在厨房的水槽里。
site n.地点，地方
The ambulance rushed to the accident site.急救车迅速赶往事故现场。
sketch n.草图；素描 v.打草稿；素描
My mother made a pencil sketch of my brother reading a book.我妈妈画了一幅弟弟读书的铅笔素描。
He sketched out a plan for his inferiors to execute.他草拟了一个方案，交给下属去执行。
skim v.①撇去②略读,掠过
We made a contest to see who could skim a flat stone over the water the farthest.我们进行打水漂比赛，看谁的扁平石头在水面上飞的距离最远。
I’ve onlyskim over his letter. I haven’t read it carefiilly yet.我只是粗略地浏览了一下他的信。我还没有仔细读。