1.simple present tense
a. use it to express a routine habit or a scheduled event that happens frequently.
e.g.1. I go to work at 8am every morning.
e.g.2. The latest MTR leaves Kowloon Bay is at 12:30am.
b. to indicate a fact
e.g. Yosemite National Park is four hours driving north from San Francisco.
2. present continuous tense
a. use it to indicate the matter which is happening at a very moment.
e.g. I am reading a very intriguing mystery novel now.
b. use it to indicate something that happen in the near future.
e.g. I am going to watch the “Nut Cracker show” tomorrow night.
c. use it to indicate something is in progress
e.g. I am going for the graduate program to become an expert in bio-engineering.
3. simple past tense
a. use it to indicate the action had been completed already.
e.g. I watched the film “Elysium” with my friends in UA Cinema last month.b. something that you used to do, but no longer doing.
e.g. I used to watch television episodes until the middle of the night.
c. indicate facts that are no longer valid.
e.g. People used dial-up method to get on the Internet in the older days, but it’s now replaced by broadband technology.
4 . future tense
a.Indicate something that happens in the future.
e.g.1. Our company will upgrade the server in the coming year.
e.g. 2. With the “Quantitative easing policy” applied in this country, this country’s economy will be deteriorated in the near future.
(Quantitative easing (QE) is an unconventional monetary policy used by central banks to stimulate the economy when standard monetary policy has become ineffective. In other words, the country just keeps printing money). I quoted the explanation of “Quantitative easing from
www.msn.com).