英语翻译：1小明说他要来,但如果他不来怎么办（what if）2你最好和医生约好时间（appointment）

Xiaoming said he would come, but what if he doesn't?

You had better make an appointment with the doctor.

He thought to buy a car if he earned enough money. 这句，我建议用He thought to buy a car if he could earn enough money. 如果原题是固定的，那还是用第一句好了。

Too many cars/automobiles will lead to (air) polution and global warming. 感觉汽车排放的尾气会直接造成 空气污染（air polution）。

Henry is a person who does deeds without regard to possible consequences.

1小明说他要来,但如果他不来怎么办（what if）
Xiaoming said he would come, but what if he didn't.
2你最好和医生约好时间（appointment）
It is better for you to make an appointment with your doctor.

3他心想着如果赚够钱就买辆车（think to）
He thinks to buy a car when he has enough money.

4太多的汽车会导致污染和全球变暖（lead to）
Too many cars would lead to the pollution and the global warming.

5亨利是一个做事不考虑后果的人（without regard to）
Henry is the guy who does things without regard to the consequences.

1小明说他要来,但如果他不来怎么办（what if）
Xiao Ming said he will come, but what if he is not?
2你最好和医生约好时间（appointment)
You better make an appointment with the doctor.
3他心想着如果赚够钱就买辆车（think to)
He think to purchase a car when he makes enough money.
4太多的汽车会导致污染和全球变暖（lead to）
Too many vehicles will lead to pollution and global warming.
5亨利是一个做事不考虑后果的人（without regard to）
Henry is a guy who does things without regard to the consequences.

英语翻译:
1小明说他要来,但如果他不来怎么办（what if）
What if Xiaoming doesn't come even he said he would?

2你最好和医生约好时间（appointment）
You' d better make an appointment with a doctor.

3他心想着如果赚够钱就买辆车（think to）
He thinks to find a way to make enough money to buy a car.
He is thinking about how to make enough money to buy a car.

4太多的汽车会导致污染和全球变暖（lead to）
Over populated cars would lead to pollution and global warming.

5亨利是一个做事不考虑后果的人（without regard to）
Henry is a person doing anything without regard to its result.
Henry is a kind of person doing anything with no regard to its outcome.

xiaoming said he would come,what if he wouldn't?
you better make a appointment with your doctor.
he thought to buy a car with enought money..
too much cars lead to global warming.
Henry is a guy who do things without regards to it.

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hope these would be helpful,thanks