I included my doubts in short sentences. Thank you.

1) What/how do you call a woman's suit made up of a jacket and a pair of trousers? I don't really know.
2) How do you call very short socks, which are completely hidden by the shoes and are usually worn in the summer? I don't really know.
3) What time are you going to the cinema (at? is a mistake if you put it at the end of the question?)
4)The Skaters usually wear large zip-up hoodies, baggy jeans and big skater (??) shoes or Nike sneakers.
5) He is known to be the man who cut the rope. (Is the passive OK?)

1. It's called a business suit, especially if it has a jacket and skirt, but jacket and pants, too. Sometimes the suit with pants/trousers is also called a pantsuit.

2. My granddaughters refer to those socks as liners. The ones that can be seen are either anklets or knee-highs, depending on how high up the leg they go.

3. Yes, "at" is not needed.

4. For clarity, I'd spell them "skater-shoes" -- or "Nike sneakers" (no hyphen needed).

5. It's fine, yes.

Different heights of socks!!

http://www.littlemissmatched.com/Catalog/girls-socks

1) A woman's suit made up of a jacket and a pair of trousers is commonly called a "pantsuit" or a "trouser suit."

To find the answer, you can use a variety of methods. One way is to search for terms associated with women's suits, such as "types of women's suits" or "parts of a women's suit." Another approach is to consult fashion dictionaries or visit reputable fashion websites to learn the specific terminology used in the industry.

2) Very short socks, which are completely hidden by the shoes and are usually worn in the summer, are often referred to as "no-show socks" or "low-cut socks."

To find this answer, you can use a similar approach as in the previous question. Searching for terms like "short socks," "socks hidden by shoes," or "summer socks" will likely provide the desired result. Again, leveraging fashion dictionaries or browsing fashion-related websites can be helpful in familiarizing yourself with different sock styles.

3) The phrase "at" in the sentence "What time are you going to the cinema at?" is unnecessary and should be omitted. The correct sentence would be: "What time are you going to the cinema?"

To confirm this, you can consult grammar rules or style guides that provide guidance on questioning structure. Additionally, observing how native English speakers construct similar questions in everyday communication can also help understand the correct usage.

4) The sentence "The skaters usually wear large zip-up hoodies, baggy jeans, and big skater shoes or Nike sneakers" seems to be grammatically correct. However, it might be more appropriate to use "skate shoes" instead of "skater shoes" to refer to footwear commonly worn by skaters.

Verifying this answer can be done by consulting fashion or skating resources, such as skateboarding magazines, skater culture websites, or even observing how skaters dress in videos or at skate parks.

5) The sentence "He is known to be the man who cut the rope" is an active sentence, not a passive one. In a passive construction, the object of the action becomes the subject of the sentence. In this case, it would be "The rope was cut by him."

To confirm the correct sentence structure, you can refer to grammar guides or language resources that explain active and passive voice. Additionally, reading books or articles that demonstrate the appropriate use of active and passive voice can help solidify your understanding.