Remove the batteries when they become weak or when the unit is not in use for extended periods. This will damage to the unit from battery leakage at such times.
第二节:语法和词汇知识(共15小题,每小题1分,共15分)
从每小题所给A、B、C、D四个选项中,选出可以填入空白处的最佳选项。
Our teachers are really ______. They often work in their office far into the night.
A. open-minded B. hard-working C. self-confident D. warm-hearted