>I have been waiting for A-mei's concert for a year already. >I have waited for A-mei's concert for a year. The first sentence means you're still waiting, so the concert either hasn't been announced yet, or it's still in the future. The second sentence implies that you're no longer waiting. Either you've given up on the concert, or you're finally going. >I haven't eaten lunch yet. >I haven't eaten lunch. These sentences are very similar. However, the first implies that you're going to eat lunch, or you have the intention to eat lunch. >The train has just left. >The train has just gone. These sentences are the same in meaning, but the first one is much more common. >I have waited you for an hour. >I have been waiting you for an hour. Really it should be "waited/waiting FOR you". I have waited for you for an hour; I have been waiting for you for an hour. The first sentence implies that you're no longer waiting - that you've given up and you're going to leave now. The second sentence implies that you're either still waiting, or the person has now arrived. (Strictly according to the tenses, this is unusual, because really the second case should always imply that you are still waiting - that the person hasn't arrived.) >She has already called me. >She has called me. (or how about 'She has called me already.') These sentences are very similar in meaning. You can change the position of "already" and it doesn't make much difference in this case. Adding "already" suggests that you're emphasising, or clarifying because someone was asking. "Sharon will call you about it soon." "She's already called me..." Hope that helps. Have a great day!