1. have difficulty (in) doing sth
结构：主语 + have difficulty (in) + 动名词
例句：
I have difficulty (in) understanding heavy accents.
She had difficulty (in) adapting to the new environment.
2. struggle with sth / struggle to do sth
结构：主语 + struggle with + 名词 / struggle to + 动词原形
例句：
Many students struggle with complex grammar rules.
He struggled to finish the project on time.
3. find it hard/difficult to do sth
结构：主语 + find it + 形容词（hard/difficult） + to + 动词原形
例句：
I find it hard to concentrate in noisy places.
They found it difficult to reach an agreement.
4. have trouble (in) doing sth
结构：主语 + have trouble (in) + 动名词
例句：
She has trouble (in) remembering names.
Did you have trouble (in) finding the address?
5. it's difficult/hard for * to do sth
结构：It's + 形容词（difficult/hard） + for * + to + 动词原形
例句：
It’s hard for me to believe this news.
Is it difficult for you to wake up early?
6. be challenged by sth（较正式）
结构：主语 + be challenged by + 名词/动名词
例句：
The team was challenged by the technical issues.
He felt challenged by learning a third language.
7. can't seem to do sth（口语化）
结构：主语 + can't seem to + 动词原形
例句：
I can't seem to solve this math problem.
They can't seem to agree on the plan.
8. have a hard time doing sth（美式口语）
结构：主语 + have a hard time + 动名词
例句：
We had a hard time convincing him.
Do you have a hard time sleeping?
9. encounter difficulties in doing sth（正式）
结构：主语 + encounter difficulties (in) + 动名词
例句：
The company encountered difficulties in expanding overseas.
She encountered difficulties (in) applying for the visa.
10. sth is a struggle for *
结构：某事 + is a struggle for + 某人
例句：
Public speaking is a struggle for many people.
Writing essays has always been a struggle for him.
其他补充表达：
It’s no picnic doing sth（非正式）: 做某事不容易
e.g., It’s no picnic working two jobs at the same time.
be at a loss to do sth: 不知如何是好
e.g., I was at a loss to explain the error.
注意：
介词 in 在口语中常省略（如：have difficulty doing）。
正式写作中建议保留 in（如：encounter difficulties in）。
避免混淆：
❌ I have difficulty to do... → ✔️ I have difficulty doing...
❌ It's hard doing... → ✔️ It's hard to do...（除非强调持续状态）
