Why does Little Brad do the clowning?
A. Because he wants to make his brother laugh.
Because he can't control it.
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What do the Customer's words mean before she provides the suggestion?
A. It means that she doesn't want Mrs. Cohen to fully understand her.
B. It means that she doesn't want Mrs. Cohen to misunderstand her.
电动汽车真空助力系统在传统真空助力系统的基础上增加了电动真空泵，来产生足够的真空度，从而实现助力。
A. 对
B. 错
电动汽车上的真空源来自于汽油发动机的进气歧管。
A. 对
B. 错
踩下制动踏板时，真空助力器连杆打开一个气门，使空气进入助力器中膜片的一侧，同时密封另一侧真空。
A. 对
B. 错
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