保管活水产品，主要取决于水中的含氧量，水中的含氧量与（）有密切关系。
A．光照
B．酸碱度
C．温度
D．水的洁净度
参考答案：C
—Amy,I called you yesterday evening,but nobody answered the phone.
—Oh,I a walk with my mother at that time. [ ]
A. take
B. took
C. am taking
D. was taking
公司所选配机型的PBE使用时间为（）分钟.
A.15
B.20
C.25
D.30
