这是一个省略了引导词‘ that’ 的宾语从句,即
The traffic rules(主句主语) say{主句谓语)(that) young children (从句主语)under the age of four and weighing less than 40pounds(介词短语作定语修饰CHILDREN) must be(系动词) in a child safety seat(介词短语作表语)
weigh变成weighing:是现在分词作定语.
这是一个省略了引导词‘ that’ 的宾语从句,即
The traffic rules(主句主语) say{主句谓语)(that) young children (从句主语)under the age of four and weighing less than 40pounds(介词短语作定语修饰CHILDREN) must be(系动词) in a child safety seat(介词短语作表语)
weigh变成weighing:是现在分词作定语.