1． 现在进行时

现在进行时表示正在发生的动作。
Keep quiet! The baby is sleeping.
(安静！娃娃在睡觉。)
现在进行时也表示即将发生的动作。
I'm tired. I'm going home now. Goodnight!
(我累了。我要睡觉了。晚安！)
Look! The bus is coming!
(看，车来了！)
My boss is leaving for South Korea.
(我老板马上要去韩国。)

2． 一般现在时

一般现在时表示真理或规律性的动作。
Rice doesn't grow in cold climates.
(寒冷的气候不适于水稻生长。)
I always go to work by car.
(我总是开车上班。)
比较现在进行时与一般现在时：前者表示正在发生的动作，后者表示经常存在的状态。
I can't understand why he is being so selfish. He isn't usually like that.
(我不明白他此刻怎么这么自私。他平时不这样。)

3． 一般过去时

一般过去时是简单陈述过去发生的事情。
We invited them to our party but they decided not to come.
(我们请了他们参加聚会，但他们决定不来。)
I was angry because they were late.
(我生气，因为他们迟了。)

4． 过去进行时

过去进行时表示过去某个具体时刻正发生的动作。
I was walking home when I met Dave.
(我碰到大卫时，我正往家走。)
Tom burnt his hand when he was cooking.
(汤姆做饭时烫了手。)

5． 现在完成时

现在完成时表示：刚刚完成的动作；曾经有过的经验；重复发生的过去动作；过去动作或状态延续至今或者强调过去动作对现在的影响。
I have just finished my work.
(我刚刚完成我的工作。)
I have never been abroad.
(我没迈出过国门半步。)
I love this movie. I have seen it ten times.
(我太喜欢这片子了！看了十遍了，我！)
I'm hungry. I haven't eaten anything since yesterday.
(我很饿了,昨天到现在都没吃过东西。)
What a boring movie/film! It's the most boring movie/film I have ever seen.
(这电影真没劲！是我看过最糟糕的电影。)

6． 现在完成进行时

现在完成进行时表示从过去开始延续到说话时一直发生的动作。
How long have you been learning English?
(你学英语有多久了？)
比较现在完成时与现在完成进行时
Mary is still writing letters. She's been writing letters all day.
(马力还在写信，她写了一整天的信。)
Mary has written ten letters today.
(马力今天写了十封信。)