Inside a car with an out-of-state license are several maps, suitcases, and bags of snacks.
A. The driver of the car is on vacation.
B. The driver of the car is on a business trip.
C. The driver of the car has children.
D. The driver of the car is on a trip of some kind.
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化学反应焓变的测定实验中为什么把0.200 mol·L-1 CuSO4溶液用移液管准确吸取,而锌粉用台秤称量?
本实验对所用量热器应有什么要求?是否允许有残留水滴?是否需要用CuSO4溶液润洗?为什么?
同一截面上各点切应力相互平行。
A. 对
B. 错
同一截面所有点的正应力都相互平行。
A. 对
B. 错