“擅自开车”，系指司机未得到车站发车人员或运转车长的（）而开车。
A、发车信号
B、出站信号
C、发车指示信号
D、行车凭证
参考答案：A
---Must we leave the classroom now?
---No, you _____. You _____ leave after the bell rings.
A．mustn't; are allowed to
B．don't have to; might
C．needn't; can
D．can't; are supposed to
脂酸β氧化酶系存在于()
A．线粒体内膜
B．细胞液
C．微粒体
D．溶酶体
E．线粒体基质
