问题
选择题
— Tommy is planning to buy a car.
— I know. By next month, he enough for a used one. [ ]
A. saves
B. saved
C. will save
D. will have saved
答案
答案:D
— Tommy is planning to buy a car.
— I know. By next month, he enough for a used one. [ ]
A. saves
B. saved
C. will save
D. will have saved
答案:D
小明利用如图所示装置和器材,探究水的沸腾特点和物质的吸热能力。
(1)小明设计的电路中的R甲、R乙必须满足的条件是___________。
(2)只闭合开关S2,观察水的沸腾,测得数据如下表:
时间(min) | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
温度(℃) | 90 | 92 | 94 | 96 | 97 | 98 | 98 | 98 | 98 |
分析数据可知,水沸腾过程中的特点为: 。
(3)断开S2,待水冷却后,继续探究物质的吸热能力。小明应控制水和煤油的___________、初温相同。且应先闭合开关 ,再闭合开关 ,并控制水的末温低于 ℃。实验表明:水的末温比油 ,水的吸热能力比油强。