在需进行持续一定时间的保压试验时，应在列车制动机按全部试验方法试验后，自阀减压（）并

甲状腺手术行硬膜外麻醉的主要危险在于呼吸抑制。

判断下面各题，对的在括号里画“√”，错的画“×”。

（1）5+5+5+5可以写成4×5。 [ ]

（2）500×80积的末尾有3个0。  [ ]

（3）210×3可以表示210个3连加。[ ]

（4）500的5倍是多少，列式是500×6。[ ]

（5）个三位数和9相乘，所得的积可能是三位数，也可能是四位数。[ ]

期货经营机构的期货业务辅助人员及其它人员的业务行为参照适用《期货从业人员执业行为准则》。（）

用所给词的适当形式填空。

1. We think the charity show is a _________ (meaning) activity and we'll take part in it.

2. Today's newspaper says _________ (clear) that middle students can only be at school for no more than

    seven hours a day.

3. They _________ (work) in the nature reserve over the years.

4. —What an interesting book!    —I have the same _________ (feel). I will read it again when I have time.

5. Edddie's mother was ill after _________ (wait) for him in the rain for a long time.

6. Timmy _________ (trap) under the stones and bricks, so he shouted for help.

7. —Where were you at this time last night?    —I _________ (write) an e-mail at home.

8. The best way to learn English is to practice _________ (speak) it.

在通信电源直流供电系统设备告警中，以下（）告警最有可能引起通信电源中断，造成通信事故？

A.直流电压过低告警

B.交流输入掉电告警

C.整流模块故障告警

D.UPS故障告警