调节变压器分接头，实质上是（）。A、改变了电压损耗的数值 B、改变了负荷变化时次级电

下列溶液：①澄清石灰水；②酸性高锰酸钾溶液；③氯化钡溶液；④品红溶液。能用来区别SO₂和CO₂气体的是 （   ）。

A．①③

B．②③

C．①②

D．②④

阅读理解。

     Hi, there! I’m Crystal Collins, and I’m very happy to share some time with you. So, you want to keep

fit, huh? Well, you surely came to the right place. Together we can keep fit and healthy, and succeed in

doing that. It’s easy. Everybody can do it, you hear? Just remember the five golden rules.

     Number one. Always wear comfortable clothes when you are exercising. You need to feel comfortable and relaxed.

     Number two. You should always do some warming-up exercises first. Get your body ready for the

real thing.

     Number three. Never try to do too much exercise too soon. Take it nice and easy now, you hear?

There’s no rush about this.

     Number four. Don’t forget to relax for about five minutes when you’ve finished your exercise. You

need to rest a little bit after you’ve been exercising.

     And here is golden rule number five. Stop at once if you feel any pain in your neck, head or any part of your body.

1. Crystal Collins may most probably be _____.

A. a teacher

B. a doctor

C. a policeman

D. a scientist

2. Crystal Collins may most probably say this _____.

A. before the exercise starts

B. when the exercise is over

C. during the exercise

D. as soon as the exercise has started

3. What does the underlined words “Take it nice and easy” in Paragraph 4 mean?

A. Don’t be nervous.B. Exercise should be beautiful.

C. Have a good rest.D. don't exercise too tiredly .

4. Which of the following is NOT true about exercising?

A. You should do some warming-up exercises before the real thing.

B. You should wear comfortable clothes.

C. You should rest for a while when you are doing warming-up exercises.

D. You should stop if you feel any pain in your body.

模型置于观测台上，当时基牙向缺隙侧倾斜时所画出的观测线为（）

A.Ⅰ型观测线

B.Ⅱ型观测线

C.Ⅲ型观测线

D.Ⅳ型观测线

拍摄高调照片，一般以（）为主。

A、顺光位

B、侧光位

C、前侧光位

D、后侧光位

与十进制数100等值的二进制数是

A．0010011

B．1100010

C．1100100

D．1100110