6. He sits around too much. He isn’t fit.
→ If he 
7. Carol didn’t answer the phone because she was studying..
→ If Carol 
8. Rita is exhausted today because she didn’t get any sleep last night.
→ If Rita 
9. She’s very thin; perhaps that’s why she feels cold so much.
→ If she
10. He never polishes his shoes, so he never looks smart
→ If he 
11. He can’t park near his office; that’s why he doesn’t come by car
→ If he
12. My house is guarded by two big dogs. That’s the only reason it isn’t broken into every night
→ If my house
13. The flats are not clearly numbered, so it is very difficult to find anyone.
→ If the flats 

giải:

6. If he were fit, he wouldn't sit around too much

7.  If Carol hadn't been studying, she would have answered the phone.

8.If Rita had got some sleep last night, she wouldn't be exhausted today.

9.If she weren't too thin, she wouldn't feel cold too much

10.If he polished his shoes, he would look smart. 

11.If he parked near his office , he would come by car. 

12. If my house weren't guarded by two big dogs , it would be broken into every night

13.If the flats were clearly numbered, it wouldn't be very difficult to find anyone

dịch:

6. Nếu anh ấy khỏe mạnh, anh ấy sẽ không ngồi quá nhiều

7. Nếu Carol không học bài, cô ấy đã trả lời điện thoại.

8.Nếu đêm qua Rita có ngủ một giấc thì hôm nay cô ấy sẽ không bị kiệt sức.

9.Nếu cô ấy không quá gầy, cô ấy sẽ không cảm thấy quá lạnh

10. Nếu anh ấy đánh bóng đôi giày của mình, anh ấy sẽ trông thông minh.

11. Nếu anh ấy đậu xe gần văn phòng của mình, anh ấy sẽ đến bằng ô tô.

12. Nếu nhà tôi không có hai con chó to lớn canh giữ thì đêm nào nó cũng bị đột nhập.

13.Nếu các căn hộ được đánh số rõ ràng, sẽ không quá khó khăn để tìm thấy bất kỳ ai