A-A+
Lighting levels are carefully controlled to fa
问题详情
Lighting levels are carefully controlled to fall within an acceptable level for optimal reading convenience.
A．ideal
B．required
C．optional
D．standard
参考答案
正确答案：A
解析：ideal理想的；required要求的；optional选择的；standard标准。因为optimal意为“最优化的”，故选A项。
