时态 - 动词的过去式

// 我打过篮球
I've played basketball.
// 我昨天学了3个单元（注意，现在完成时不可以加yesterday，last year等词语）
I studied 3 sections yesterday.
// 我去年去过美国
I went to the US last year.
// 我今天没刮胡子（用于晚上说，表示今天已经结束了，我今天不会再刮了）
I didn't shave today

问：Let us watch The Avengers.(我们去看复仇者联盟吧)
答：I watched that.(我之前看过，就是单纯的看过，至于这次想不想看我还没有决策，仅用作陈述)

// 那时我已经打完篮球了
I had played basketball.
// 她来之前，我们就已经打完篮球了
// （两件事，她来，我们打完球，她来距离当前时间最近，所以用一般过去时，我们打完球，距离当前时间远，所以用过去完成时）
She arrived after we had played basketball
// 电话响之前，他已经睡了
// （两件事，电话响，他睡了，电话响距离当前时间最近，所以用一般过去时，他睡了距离当前时间远，所以用过去完成时）
He had slept a little before the phone rang
lt had started to snow by 10 p.m. yesterday.
They had left for Beijing by this time yesterday

// 那会我正在打篮球
I was playing basketball.
// 当她到的时候我们正在打篮球
// （更短的那个使用一般过去时，她到的时候和打篮球比，明显更短暂，所以she arrived用一般过去时）
We were playing basketball when she arrived
// 电话响的时候他正在睡觉
// （更短的那个使用一般过去时，电话响和睡觉比，明显更短暂，所以phone rang用一般过去时）
He was sleeping when the phone rang
It was snowing at 10 p.m. yesterday
We were flying to Beijing at this time yesterday

// 那会我正在打篮球
I had been playing basketball
We had been playing basketball for an hour when she arrived
He had been sleeping for a long time when the phone rang.
It had been snowing for several hours by 10 p.m. yesterday.
They had been flying to Beijing for 2 hours by this time yesterday.

// 他昨天去了公园
He goes to the park yesterday.
// tom10年前来到了这里
Tom arrived here 10 years ago.
// 他们昨天很晚才回家
They usually came back home late.
// 杰瑞在5岁的时候，吃午饭之前总是吃奶酪
Jerry always ate cheese before lunch when he was 5.
// 他过去常常喝多了（used to do something表示过去常常如何如何）
He used to drink a log.
// 我很喜欢TYC，直到她离开了北京
I liked tyc until she left there.

// not AA until BB表示直到BB才AA
// 直到她离开了这里，我才喜欢TYC
// did已经成为了过去式，所以动词like不需要变成过去式
I did not like TYC until she left there.