变压器作空载实验，要求空载电流一般在额定电流的（）左右。
A.5％
B.10％
C.12％
D.15％
参考答案：A
已知函数f（x）是定义在R上的奇函数，当x≥0时，f（x）=x（1+x）．
求：（1）f（x）的解析式．
（2）画出f（x）的图象．
I have _____ friends at school. I like playing with _____.[ ]
A. much; they
B. many; them
C. a lot of; their
D. lots of; theirs
