考博考试

【单选题】You don't have to install this radio in your new car. It's an ______ extra
A. excessive
B．optional
C．additional
D．arbitrary
网考网参考答案：B
网考网解析：
[解析] A项excessive意为“过多的；过分的”；B项optional意为“选择的；非强制的”；C项additional意为“额外的；附加的”；D项arbitrary意为“霸道的；武断的”。 查看试题解析出处>>