The word "therefore" is used when you have evidence and you want to make a statement based on that evidence. Example: My business did not make any money last year, therefore I will have to close it down. "Therefore" is fairly formal, an informal substitute is the word "so". My business did not make any money last year, so I will have to close it down. I hope this helps :)

I think you are getting confused between the past and future tense. If you say: "When I got married, I had 3 kids" this happened in the past. Someone can say: "When I am married, I'll have 3 kids" or "When I marry, I'll have 3 kids" This means that they plan to have 3 kids after they get married. I hope this helps :)

It's hard to perfect the sentence without context, but I would rewrite it to: Because the survey is still in progress, more people may still participate. Therefore, she has not yet evaluated the questionnaire.

I have never heard this word, and there is no reference to it in the English dictionary.

This is a very scientific sentence that many native English speakers may not fully understand. When conducting experiments, you need to control variables - which could be anything. For example, if you are testing out a new medication on people to see if there are side effects, you may want one of your "controls" to be that the people testing it cannot be on any other medication. There are an infinite amount of variables depending on which experiment you are referring to. Replication means to do the experiment more than once to make sure that your results are valid. I hope this helps

If you speak Chinese, and you are learning to speak English, then you would find someone who is learning Chinese and already speaks English. Then the two of you will help each other learn each language for no cost.

Remember that serve means "to provide service". What service does a journalist provide to his readers? A journalist is supposed to provide readers with an honest and objective account of what he his reporting. So in this context, I believe it would mean that the journalist should remember he must report the truth because that is what the readers want.

I would say the last 2 are correct, but don't forget to add the word "of": We have a tiring schedule ahead of us We have a tiresome schedule ahead of us I've never heard the word "wearisome" used in that context. I hope this helps :)