填一填。

①君子喻于义，____②天下无难事，____​。

    I think that the world will be an easy place to live in. We1have machines and robots and they will2us do all the3jobs, and we don't have to do things4washing dishes and5the beds, though we won't have any dishes at all. Maybe we will just throw the dishes away after each meal. I6that doctors will be able to7us alive8a long time. I hope that when I am 80 years old, there9something that can keep me alive for1080 years, so I will live to be 160 years old.

如图，在平面直角坐标系中，点A在第二象限内，点B在x轴上，∠AOB=30°，AB=BO，反比例函数y= $\frac{k}{x}$ （x＜0）的图象经过点A，若S_△ABO= $\sqrt{3}$ ，则k的值为____．