If the doctor had been available, the child ()
A. would not die
B. could not have died
C. might not die
D. should not have died
基本农田保护区划区定界的基本单位是()。
A. 村级
B. 乡(镇)级
C. 县(市)级
D. 省(自治区、直辖市)
海上无线电话移动业务在中频(MF)的频率范围是()。
A. 4-27.5MHz
B. 3-30MHz
C. 1.605-4MHz
D. 156-174MHz
水平层理、斜交层理、交错层理均有发育沉积或岩层()。
A. 陆相
B. 海相
C. 过度相
D. 沉积接触