关于马自达轿车四轮转向系统失效保护，下列那项叙述是不正确的（）
A.油压异常
B.信号异常
C.电磁阀异常
D.滑阀卡滞
参考答案：D
The question is very _____. I can't find the answer. [ ]
A. relaxing
B. interesting
C. difficult
D. exciting
来自黄热病疫区的飞机，机长或其授权代理人须主动出示有效的灭蚊证书。( )
