吗啡需注射给药的原因是：
A．首关消除明显B．口服刺激性大C．口服不吸收D．口服易被胃酸破坏E．口服易被肠道破坏
参考答案：A
If you still have a problem, you can ask the police ______ help. [ ]
A. for
B. on
C. in
D. at
