心身疾病与下列哪些因素有关
A．情绪B．生活事件C．性格D．个体易感性E．以上都是
参考答案：E
25. – Tom, it's too late. Our son ________ be back.
– Don't be anxious. I dare say he ________ have some extra work to do.
A．can; must
B．will; might
C．should; must
D．must; may
启动时为什么先送轴封后抽真空，为什么抽真空后再关真空破坏门？
