Would it sound awkward if I say "had ever met" instead of "have ever met?" If so, could you tell me why?

How can I describe fractions like 1/5, 1/143 in English?

There are several different ways to describe fractions in English. One way is to say the first number normally and the second number you add a -th, -rd or an -nd at the end of it. For example, 1/5 is said one fifth. Another way that it could be said is if the first number is a one, you can just say the second number and add the proper ending such as a fifth. Here are some more examples. Ex: 2/3 is two thirds Ex: 3/7 is three sevenths Ex: 1/2 is a half (this is the only way to say this one) Ex: 4/5 is four-fifths Ex: 1/25 is one twenty-fifth Ex: 1/8 is one eighth or an eighth 1/143 is a little trickier. You would say one and one hundred and forty third. You could also say one out of one hundred and forty-three.

Would it sound awkward if I say "had ever met" instead of "have ever met?" If so, could you tell me why?

It would sound a little odd, yes! That's because "had" is the past-tense form, whereas "have" is the present-tense form. So if it were "had," it would sound like the person is no longer the best salesperson they've met. "Have" means that he still is the best salesperson. Ex: She had been a good friend until she lied to me. Ex: She has always been a good friend to me. Ex: This is the best cake I have ever eaten.

Can I say "this job is for a grown-up"? What is the difference?

Yes, you can say "this job is for a grown-up." The sentence meaning stays mostly the same, with only the grammar pattern itself being different.

Is "go grab some lunch" used commonly in daily conversation?

Yes, "grab some lunch" or "grab" any meal or food is used in daily conversation a lot because it is very casual and informal. It also expresses that you are going to go get lunch or a meal very quickly, so it often refers to buying pre-made food or eating in a way that does not take a lot of time or effort. Ex: Are you hungry? Let's go grab some dinner. Ex: I'm gonna go grab some breakfast on the way to work. Ex: Do you want to grab a coffee real quick?

What does "to mark its wearer" mean here? I don't really understand the connection of "to mark" and "its wearer".

The phrase "to mark (someone or something) as (something)" is usually used to means that something, in this case lipstick, is a sign or expresses something about that thing or person. "Its wearer" simply means the person (wearer) who has on lipstick (it's). "Marks its wearer" means that something that a person is wearing is a sign to others is something. Ex: The badge marks its wearer as a member of the police force. Ex: This hat and gown marks us as graduates.