Sure, here are the transformed sentences:

**Sentence transformation 20B**

1. Did they build the garage at the same time as the house?
- Was the garage built at the same time as the house?

2. The people who were at the meeting will say nothing to the press.
- Nobody who was at the meeting will say anything to the press.

3. The heavy rain made it impossible for us to have our picnic.
- We were unable to have our picnic because of the heavy rain.

4. Joan will stay on at school unless she finds a good job before September.
- If Joan doesn't find a good job before September, she will stay on at school.

5. I don't really want to go out tonight.
- I'd rather not go out tonight.

6. Shirley didn't begin to read until she was eight.
- It wasn't until she was eight that Shirley began to read.

7. Lucy hasn't worn that dress since Barbara's wedding.
- The last time Lucy wore that dress was at Barbara's wedding.

8. Let's go abroad for our holiday this year.
- Why don't we go abroad for our holiday this year?

9. He is such a slow speaker that his students get very bored.
- He speaks so slowly that his students get very bored.

10. Mackenzie wrote four best-sellers before he was twenty.
- By the age of twenty, Mackenzie had written four best-sellers.

**Sentence transformation 21B**

1. She asked John how he liked her new dress.
- "How do you like my new dress?" she asked John.

2. A train leaves at 8 o'clock every morning.
- There is a train that leaves at 8 o'clock every morning.

3. He stole some money and was arrested for it.
- He was arrested for stealing some money.

4. She met Mike when she went to Spain for her holiday last year.
- She wouldn't have met Mike if she hadn't gone to Spain for her holiday last year.

5. Someone should do the job tomorrow.
- The job should be done tomorrow.

6. I've never met a more dependable person than Roger.
- Roger is the most dependable person I've ever met.