1.带有 -ing 的单词
看到或听到以 -ing 结尾的单词时，有三种可能：它是一个形容词、动名词（以 -ing 结尾的名词）或动词进行式。
Adjectives
My job is unchallenging. 我的工作毫无挑战性。
My work with the Peace Corps was very rewarding. 与和平队共事非常有意义。
动名词
Working during the day and studying at night isn't easy. 白天工作晚上学习很不容易。
动词
I am studying to become a teacher. 我正在为成为一名教师而学习。
He was working in a bank when he decided to change his career. 决定
跳槽时，他正供职于一家银行。
2.非真实条件句
使用非真实条件句说明非真实的未来境况、想象的或不可能发生的事物。在 if 引导的分句中使用一般过去时，并在结果分句中使用 would + 动词原形。
If I had a lot of money, I'd travel around the world. 如果我有很多钱，我就会环游世界。
如果结果分句出现在于 if 之前，则无需逗号(,)。
I'd travel around the world if I had a lot of money. 如果我有很多钱，我就环游世界。
非真实条件句中动词 be 的正确一般过去式是 were。
If he were a teacher, he'd be happier. 如果他是教师，他就会更加开心。
If they were younger, they'd travel around the world. 如果他们再年轻一些，他们就会环游世界。
但是，在俗语中，你将经常听到 was。
I'd be a basketball player if I was taller. 如果我能高一点，我就是篮球运动员了。
