在PS48300型开关电源系统中，防雷器的响应时间为（）ns。A、大于25 B、小于

当委托人和承包发生争议时，监理机构应根据自己的职能，以（）的身份判断，公正地进行调解。

A．委托人 

B．承包人 

C．独立 

D．双方

选择最佳答案。

1. —             

    — Nice to meet you, too. [ ]

A.  Hello!

B. Nice to meet you.

C. Good morning!

2. — Let's go to school.

    —             [ ]

A. Really?

B. Bye!

C. OK!

3. — I have a crayon.

    —                        [ ]

A. This is a pen.

B. Me too.

C. OK!

4. — What's your name?

    —                   [ ]

A. My name's Mike.

B. This is Mike.

C. Nice to meet you, Mike.

5. — Where is your ruler?

    —                         [ ]

A. This is my ruler.

B. Here it is.

C. I have a ruler. 

6. — Hi!  I'm Zhang Nan.

    —                      [ ]

A. Let's go to school.

B. Nice to meet you.

C. Fine, thank you.

7. — Shake your body.

    —                    [ ]

A. Thank you.

B. OK!

C. Clap your hands.

8. — Let's make a puppet.

    —                        [ ]

A. Good idea.

B. Goodbye.

C. Let's go.

9. — Good afternoon.

    —                    [ ]

A. Good morning.

B. Good afternoon.

C. Good evening.

10. — Happy Halloween!

      —                      [ ]

A. Happy Teachers' Day!

B. Thank you! Happy Halloween.

C. That's OK.

关于矿产资源及其主要分布国，下列对应错误的是：

A.硝石：加拿大 

B.磷矿：摩洛哥 

C.铜矿：智利、秘鲁 

D.金矿：南非

胸围和头围相等的年龄（）。

A．新生儿

B．8个月

C．1岁

D．1.5岁

E．2岁

“气锁”，即在抽汲时由于气体在泵内（），使吸人和排出阀无法打开，出现抽不出油的现象。