载脂蛋白B48主要存在于（）
A.HDL
B.LDL
C.VLDL
D.CM
E.FFA
参考答案：D
270000000读作：______；
270000000≈______亿．
Jack’s mother was twenty-seven when he was born. Jack is eleven this year. How old is his mother?
A．56
B．49
C．38
D．40
