夜间施工，进入施工现场的人员必须穿着（）的服装、携带（）方可上线。
参考答案：带反光标志；照明灯具
David failed in the final examination last term and only then________how much time he had wasted
before.[ ]
A. had he realized
B. he had realized
C. did he realize
D. he realized
关于羊水过多的病因有()
A．胎儿神经管缺陷性疾病
B．多胎妊娠
C．糖尿病
D．胎儿消化道畸形
E．肾缺如
