随机变量ξ等可能的取值1，2，3，…，n，若P（ξ＜4）=0.3，则n的值为 [ ]
A．3
B．4
C．10
D．不确定
答案：C
计算下列各题
编码细胞色素C(104个氨基酸)的基因有多长(不考虑起始和终止序列)
---Didn’t the neighbour see the man breaking into the house?
---No, she ______ in the other direction.
A．had looked
B．was looking
C．looked
D．is looking
