邓小平有一两句名言，一句是“摸着石头过河”，一句是“看准了，就大胆地试，大胆地闯。也就是说，要具备理论创新的巨大勇气，敢于走前人没有走过的路，大胆地向前闯，大胆地去实践。这表明（  ）

    It is interesting to visit another country, but there are some problems when we don't know the 1very well.It may be 2 to talk with the people there. We may not know how to use the telephone in the country that we are visiting. We may not know how to buy 3 we need. In a4country we might not know where to eat or what to order in a 5 It is not easy to decide how6to tip (给……小费) waiters or taxi drivers. When we need help, we might not know how to ask for help.It is not pleasant to have an experience7that. 8a short time, however, we learn what to do and what to 9We learn to enjoy life in another country and then we may feel 10 because we have to leave.

①b²＞4ac；②2a+b=0；③3a+c=0；④a+b+c=0．

其中正确结论的个数是（   ）

按照题目要求作图：