关于多普勒频移与探头发射频率,叙述正确的是()
A.两者无关
B.两者成反比
C.两者成正比
D.前者与后者的二次方成正比
E.前者与后者的二次方成反比
参考答案:C
Principal White has been working in the school for about 20 years, ____all his energy to teaching and researching as well as the running of a healthy school.
A.devoted
B.devoting
C.to devote
D.devote
组胺在炎症灶内最主要的作用是
A.白细胞趋化
B.使血管扩张和通透性增高
C.引起疼痛
D.导致发热
E.造成组织损伤