题干
.
A lot of tents, drinking water and food __________ to the homeless earthquake survivors in the past several weeks.
A lot of tents, drinking water and food __________ to the homeless earthquake survivors in the past several weeks.
A：are sent
B：were sent
C：have been sent
D：had been sent
答案(点此获取答案解析）
C
2KCl＋3O2↑，反应后从剩余物中回收纯净的二氧化锰的操作顺序正确的是（已知MnO2为黑色难溶于水的固体）（ ）
上的奇函数
满足
，则
的值为（ ）
