sure***** a.确信的；必定的
e.g: I'm not sure whether I should tell you this. 我拿不准该不该把这事告诉你。
ensure**** vt.保证，确保；使安全； en-(使...)
e.g: please ensure (that) aii light are switched off. 请务必将所有的灯都关掉。
insure** vt.给...保险；确保；保证；vi.投保；确保； in-(在内）
e.g: The painting is insured for $ 1 million. .这张油画投了100万美元地保险。
assure** vt.(向...)保证；使确信； as-（=ad-,to)
assuring a.保证的；确信的；使人有信心的
assurance*** n.保证，担保；保险；确信，自信
e.g: You think I did it deliberately,but I assure you (that) I did not.你认为我是故意干的，不过我向你保证不是的。
reassure** vt.使安心；使消除疑虑；给...再保险
e.g: The doctor reassured him that there was nothing serious wong.医生安慰他说，没有什么严重的病。
