1. The doctor was tallcing to a woman who was having a baby.(x)
The doctor was talking to a woman who was expecting a baby. (√)
having a baby可兼指“怀孕的”和“正在生孩子”。为避免混淆，应使用expecting a baby或pregnant来表示“怀孕的”。
2. Once you marry that guy, there will be no going backward.(x)
Once you marry that guy, there will be no going back. (√)
no going / turning back意为“无法回头”，是一种比喻的说法，为固定用语。backward作副词时，指方向上的“向后”，如:I glanced backward to see what happened.(我向后看了一眼以了解发生了什么事。)
3. Don't speak ill of others behind their back.(x)
Don't speak ill of others behind their backs. (√)
behind one's backs)，意为“在某人的背后”，须配合单复数变化使用。
4. I've got a photo of that rock star with his autograph in the back.(x)
I've got a photo of that rock star with his autograph on the back. (√)
on the back (of sth)是指“在某物的背面”。in/at the back (of sth)通常是指在书本或报纸的最后几页，如:Refer to the index in the back for technical terms.(专业术语请参阅书后的索引。)
5. You cannot imagine how bad I need the money.(x)
You cannot imagine how badly I need the money.(√)
need / want sth badly是“非常需/想要某物”的意思，为固定用法。
6. They all believe the election is in a bag.(x)
They all believe the election is in the bag.(√)
be in the bag = be certain to be won or achieved,意为“一定能赢或成功”，是固定用语。
7. How many baggages do you have?(x)
How many pieces of baggage do you have? (√)
baggage或luggage(英式用法)是“行李”的集合名词，不可数。要表达件数时，须用a piece / two pieces of baggage。
8. Don't forget to go to the baggage's claim. (x)
Don't forget to go to the baggage claim. (√)
“机场领取行李处”的固定用语为baggage claim(美式用法)或baggage reclaim(英式用法)，baggage后不加 ’s。
9. The suspect was released on a bail. (x)
The suspect was released on bail. (√)
bail是“保释金”，为不可数名词。
10. You ought to get a balance between work and play.(x)
You ought to strike a balance between work and play. (√)
strike a balance (between...)是“在两者之间取得一个平衡”，为固定用法。