机体获得人工被动免疫的方式是
A．隐性感染B．疫苗接种C．显性感染D．注射抗毒素E．注射类毒素
参考答案：D
The father has been ____ for many years in order that his only son can be ____ with higher education.
A．fighting; served
B．struggling; equipped
C．working; offered
D．laboring; received
我船航向060°，某船位于我船右舷10°，距离8nmile，若该船航向为220°，两船保向保速，则5min后，我船位于该船舷角（圆周法度量）（）。
A．增大
B．减小
C．不变
D．不确定
