尿碘是监测碘营养水平的公认指标。
参考答案:对
When the old man_____to walk back to his house,the sun____itself behind the mountain.
A.was starting;hid
B.had started;had already hidden
C.had started;was hiding
D.started;had already hidden
获得威尼斯影帝的华人男演员是(),他当年只有16岁,主演的影片是《阳光灿烂的日子》。