题目

A.now and then B. safe C.unless D.because E. detailsRemember your favorite websites by using the history button and the bookmark function on your computer. This is a way that your digital footprint can work in your favor, but remember to clear your browser history 【1】.Be careful about whom you are communicating with and always think twice before telling 【2】 like your home address, phone number, etc. to someone else.Now, it’s quite common for companies to check out the online information of possible candidates（申请人）. In many cases, companies choose the right persons not 【3【选修4-1：几何证明选讲】如图，已知AD，BE，CF分别是△ABC三边的高，H是垂心，AD的延长线交△ABC的外接圆于点G．求证：DH=DG．