You are correct. "Has gone to China" can indicate that he went to China and still hasn't come back. "Went to China" just indicates that the action of going to China has happened. Depending on the context of the conversation, he may have come back from China or is still there. For example, if we are at work chatting and this conversation happens: You: "I'm looking for John, is he around?" Me: "No. He went home." I could have said "No. He has gone home." as well but it's a bit formal. Because you and I are at work and I said he wasn't, it's already clear from the conversation that John hasn't come back.

1. You can think of it as "On the last day of last March..." So on the last day of March, what conditions were true? You had been studying English for five years. It's an action that started sometime in the past and it continued at least through March. It may or may not have stopped since then. 2. Answer B (That what I want) needlessly puts in the definite article "that." "that what/that which" is a common mistake I see in French and Spanish speakers who try to translate word for word into English. Answer C is incorrect because of the ordering. "What do I want is too expensive" is a badly formed question. "What I do want is too expensive" could work. It's slightly awkward and wordy but it's OK. Answer A is the best out of the three. 3. Either could work. 4. This is a bit of a trick question. This isn't singular or plural, it's a weird quirk of English and a verb tense that is not used often, the subjunctive. It expresses opinion, hypothethical situations, emotion, and some polite requests. It's is essential that Alice" remind/ reminds/ must remind" him. "must remind" is out because it is stating the same thing(redundant) as "essential". So that leaves remind and reminds. "reminds" in the fragment "Alice reminds" would the present indicative, or a statement of fact for something that is happening. "remind" in the fragment "that Alice remind" is the present subjunctive. Even though you think it's really important that Alice remind him, it's not something that has happened yet. A is the correct answer. http://www.englishpage.com/minitutorials/subjunctive.html https://en.wikipedia.org/wiki/English_subjunctive https://en.wikipedia.org/wiki/Grammatical_mood#Realis_moods 5. I don't have even of the sentence to tell you.

As Nothin said, it's the first one. I am a native English speaker.

As others have mentioned, outside the military and period tv shows and film, the use of aye is mostly outdated. "Aye-aye sir" is a common response to an order from a commanding officer in some branches of the military. Celebrating Talk Like A Pirate Day (September 19) is another time when you might hear it. I've also seen folks use the eye emoji in texts to indicate yes because eye sounds like aye which means yes.

Collaboration means that multiple people are working together towards a common goal. So if you have a group project with several classmates, you all are collaborating.Teams often collaborate when creating a new thing or collectively deciding strategy. Cooperation can also be multiple people working together but it can be one-sided. If an employer requires people to submit to a background check, you are cooperating with their request. It's more so a demand but that's another story. Another example of cooperation is the fact that to accomplish my goals, I need some help from other departments. I work with them to make sure my work gets done but at the end of the day, whether or not it happens is not of their concern.