问题
单项选择题
The traffic rule says young children under age four and () less that 40 pounds must be in a child safety seat.
A. being weighed
B. to weigh
C. weighed
D. weighing
答案
参考答案：D
解析：
young children和weigh构成主谓关系，所以排除A和C。不定式表示 的，应用现在分词作定语。故选D。