近年来，无锡瞄准打造制造业基地的目标，积极打造“三谷”等一批高新技术产业基地，“三谷”指的是什么？
参考答案：
“硅谷”、“液晶谷”、“药谷”
已知圆C：x2+y2-4x-6y+12=0，求过点A（3，5）的圆的切线方程．
Knowledge and learning are important if we want to be successful, but they may also ______ our
thinking. [ ]
A. direct
B. limit
C. change
D. improve
