It's time _________ breakfast. [ ]
A. for
B. having
C. have
D. to has
答案:A
Jim and I ___________ know her family name.
A. am not B. aren't C. don’t
蓄电池使用的()是保证电池正常寿命的关键。环境温度过高,蓄电池中的化学反应加剧,在充电过程中蓄电池的减压阀会频繁开启加速失水速度,从而降低蓄电池寿命;放电深度以及放电电流和终止电压与蓄电池寿命之间的关系也是非常密切的。
A.环境温度,放电深度;
B.充放电电流;
C.电池容量的合理配置;
D.定期维护;