避免婴儿偏食、厌食要把握婴儿的（）特点。
A、性格
B、兴趣
C、心理
D、身体
参考答案：C
已知一组数据共100个，在频数分布表中，某一小组的频数为4，则这一小组的频率为______．
However _____ they are designed, pens should function as a tool to write with.
A．differ
B．difference
C．different
D．differently
