IPV4的地址格式由多少个字节组成？（）
A.1个字节
B.4个字节
C.2个字节
D.8个字节
参考答案：B
He has been working hard for 6 days，________a lack of concentration in the meeting.[ ]
A．resulting in
B．resulted in
C．resulting from
D．resulted from
起苗时一般落叶乔木可裸根挖掘，但常绿树必须（）。
