In this article , you need to back up general statements with ________ examples.
A：specific
B：permanent
C：abstract
D：universal
Cathy was born blind（天生是盲的）, so she has __________ seen our beautiful world.
欧洲西部的北、西、南三面分别濒临
已知函数f（x）=2cos2x+3sin2x﹣1．
（1）求f（π6）的值；
（2）求函数f（x）的最小正周期和单调递增区间．
