我国自然资源的基本特征是总量________________,人均________________。
丰富 不足
The Town Hall _____ in the 1800's was the most distinguished building at that time. [ ]
A. to be completed
B. having been completed
C. completed
D. being completed
外照射监测方法中的操作监测是指在某些涉及到放射性物品的操作开始时所进行的监测。