钩端螺旋体基本的病理改变是()
A.全身毛细血管损伤
B.全身单核-巨噬细胞系统的增生性反应
C.肝细胞病变
D.淋巴组织的良性增生
E.变态反应
参考答案:A
Bob would have helped us yesterday, but he ____________.
A.is busy
B.had been busy
C.has been busy
D.was busy
一个热水器内盛有20 kg的水,吸收了2.52 ×106J的热量后,水的温度升高到55℃,水的初温是多少摄氏度?[c水=4.2×103 J/(kg.℃)]