A:过滤
B:观察颜色、状态
C:利用丁达尔效应
D:闻气味
The boy is _________ young to know ________.
are my legs. ( )
俄罗斯下列矿产地中,盛产铁矿的是
看图 ,判断句子是否正确并修改
The present is in the desk____