though, although
1 作为连词，though和although通常可以互换使用，但although语气较重，通常放在句首，并用于正式场合。例如：
Although it was snowing, it was not very cold. 虽然下着雪，但并不是很冷。
2 用though时，可将强调的词前置，但although没有此用法。 例如：
Fond though I am of operas, I don't want to see one every weekend. 虽说我很喜欢歌剧，但我也不想每个周末都去听一场。
3 though可用于even though / as though 等结构中，although则不能。例如：
Even though I fail, I'll keep on trying. 即使失败，我也会继续尝试下去。
You look as though you know each other. 看起来你们好像彼此认识。
4 though可用于省略句。例如：
Though (he is) alone, he is very happy. 虽然孤身一人， 但他很快乐。
5 although只用作连词，而though 除作连词外，还可用作副词，意为“可是；但是”，常置于句末；句子较长时，也可置于句中。例如：
It's hard work. I enjoy it, though. 这是苦差事，可我干得挺开心的。
There's no excuse, though, for hurting her feelings. 但是，伤害了她的感情，这是无法原谅的。
These things did not happen to these people because they were lazy or stupid. They happened because of addiction. (Para. 5)
Meaning: These things happened to these people, but it was not because they were lazy or stupid, but because they had addiction to the Internet.
Sentence structure note:
do / did not+verb+because…这个结构表示“…发生，但不是因为…”， 其中not不是用来否定主句的谓语动词，而是用来否定由because引导的状语从句。例如：
I did not accept John's gift because I liked him. 我收下约翰的礼物并不是因为我喜欢他。
注意：这种结构有时会产生歧义。例如：
I didn't sing because Pam was there. 我不是因为帕姆在那儿才唱歌的。
这个句子在某种语境下，也可以理解为：“我没有唱歌，因为帕姆在那儿。”
为了避免误解，表示“我没有唱歌，因为帕姆在那儿”，英语应为：Because Pam was there, I didn't sing.
During their very first term, their grades can plunge, their health decline, and their friendships cease. (Para. 5)
Meaning: In their first term of college, their grades can drop quickly, their health can become worse, and their friendships can end.
Note: At a British school or university, a school year is divided into three terms. At an American university, there are two semesters or four quarters.
22 These rewards are not actual, useful, real-life rewards, but simple stimulation that arouses positive feedback in the brain. (Para. 7)
Meaning: These rewards are not real, useful rewards, but only simple stimulation that brings about positive effects in the brain.
stimulation: n. [U] 兴奋；刺激；激励
Young children need stimulation, so parents should often encourage them. 年幼的孩子需要激励，所以父母应该常常鼓励他们。
arouse, arise, rise, raise
1 arouse: vt. 1) 表示“引起；激起；唤起”，可用于被动语态。例如：
arouse one's interest / sympathy / anger / anxiety / concern / enthusiasm / opposition, etc. 激起 / 引起 / 唤起某人的兴趣 / 同情心 / 愤怒 / 焦虑 / 担心 / 热情 / 反对等
His revolutionary work in linguistics has aroused intense scholarly interest. 他在语言学上创新性的工作激起了学者们的强烈兴趣。
2) arouse sb. 唤醒某人
About two o'clock, we were aroused from our sleep by a knocking at the door. 在两点钟的时候，有敲门声把我们从睡梦中弄醒。
2 arise (arose, arisen): vi.
1) 意为“产生；发生；出现”，常用于说明抽象事物。例如：
problem / trouble / quarrel / difficulty / misunderstanding / disagreement, etc. arises问题 / 麻烦 / 争论 / 困难 / 误解 / 分歧等出现 / 发生 / 产生
A completely new situation will arise when the new examination system comes into existence. 新的考试制度出台后，将出现全新的局面。
2) 常用短语：arise from / out of sth. 由…引起；因…产生。例如：
They are talking about problems arising out of the lack of communication. 他们正在谈论由于缺乏交流而产生的问题。
3 rise (rose, risen): vi.
rise使用范围较广，一般不用于被动语态。
1) 表示“上升；增长”。例如：
The water level rises rapidly during the rainy season. 在雨季水位上升很快。
The increase in prices is needed to meet costs that have been rising. 需要通过涨价来解决不断上涨的成本问题。
2) 表示“起立；起身；起床”。例如：
He rose to greet Mary, who he hadn't seen for a long time. 他起身去迎接玛丽，他很久没有见过她了。
They had risen at dawn. 他们黎明时就起床了。
4 raise: vt.
1) 表示“举起；提起；提高”。例如：
Two incidents in recent days have raised the level of concern. 最近发生的两起事件引发了更大的关注。
This country is expected to raise interest rates. 该国预计会提高利率。
2) 常用短语：raise an army招募军队；raise a family 养家；raise salaries / the rent提高工资 / 租金；raise one's hand举起手；raise a question提出问题；raise funds 筹集资金
