【现在进行时】
1. 表示现在 (说话瞬间) 正在进行或发生的动作。
[例句] He is reading a newspaper now.
2. 表示当前一段时间内的活动或现阶段正在进行的动作 (说话时动作不一定正在进行)。
[例句] What are you doing these days?
3. 表示说话人现在对主语的行为表示赞叹或厌恶等, 常与always, constantly, continually等副词连用。
[例句] He is always thinking of others.
4. 表示在最近按计划或安排要进行的动作。常限于go, come, leave, start, arrive等表“移动”、“方向”的词。
[例句] He is coming to see me next week.
【过去进行时】
1. 表示过去某时正在进行的动作。
[例句] He was sleeping when Mary came to see him.
2. 动词go, come, leave, arrive, start等的过去进行时常表过去将来时。
[例句] She said she was going to Beijing the day after tomorrow.
【一般现在时】
1. 表示现在习惯或经常反复发生的动作或存在的状态, 常与usually, always, sometimes, often, every day / week / month / year等时间状语连用。
[例句] He often does his homework in his study.
2. 表示主语现在的特征、性格和状态。
[例句] The dictionary belongs to me.
3. 表示客观规律或科学真理、格言, 以及其他不受时间限制的客观存在。
[例句] The moon goes around the sun.
4. 在有连词if, unless, before, as soon as, when, once, however等引导的时间、条件和让步状语从句中, 用一般现在时表将来。