大概grammar

• 我大概明白你的意思。(I don't understand what you're saying completely but I get the gist.)
• Dialogue:
• A：你打了多少个电话？ (How many phone calls did you make?)
• B1：大概50个。(Approximately 50. The structure is 大概+number+measure word.)
• B2：50个左右。(50 or thereabouts.The structure is number+measure word+左右.) 

Here's another example of how using 大概 and 左右 are approximately the same but have a different connotation:

• A：你的车买了多少钱？
• B1: 大概三十万人民币。(Around 300,000RMB.)
• B2: 三十万人民币左右。(300,000RMB more or less.)

In this example, 大概 implies the speaker is unclear or uncertain about the amount, or perhaps they don't remember. The use of 左右 implies a greater level of accuracy or certainty on the part of the speaker but they don't care to go into greater detail. The listener could press the speaker for more detail, in which case they would follow up with a more exact number if they were able.

1. 他_________是个中国人。
2. 他走路摇摇晃晃的，_________是醉了。
3. 他_________知道要说些什么。
4. 今天中午有20摄氏度_________。
5. 他30岁_________。
6. UB _________有3000多国际学生。
7. 这辆车很省油，加一次油_________可以用两周。
8. 我今天两点_________到学校。
9. 都两点一刻了，他还没有到，_________是路上堵车。
10. 意大利面，一般要煮9分钟_________。

1. 起床
2. 洗澡
3. 吃早饭
4. 上班
5. 吃午饭
6. 下班
7. 吃完饭
8. 睡觉

Jenie specializes in teaching Chinese for daily use, for business, and to prepare for taking the HSK test. She is skilled at helping students understand Chinese grammar, how to practice, and how to remember what they study effectively. She has lived abroad and has taught professionals from major multinational corporations. Well qualified, she graduated from a college that focuses on foreign language teaching and continues to participate in professional development programs for teaching Chinese.

I often read and hear 大概 but I cannot work out its exact use. According to my dictionary it can be a noun meaning "general idea", an attributive  meaning "approximately" and an adverb meaning "probably". But this doesn't seem to explain the meaning of 大概 when I see it used. For example, I just read a line "他大概很奇怪". In my mind all hear is "He was approximately strange" or "he was in general a bit strange". None of these translations really seem and/or feel appropriate. In fact, I often feel that if I just skip 大概 the sentences I read and hear are more "correct" EG "他很奇怪". Is anyone able to help me understand the meaning/nuance of 大概, and explain its usage?

大概 (dàgài) and 大约 (dàyuē) are adverbs that can often be used interchangeably to mean probably, about, or approximately. Both are used in informal/formal settings. A key difference between these words is that 大概 has a much wider use, as it can be used as a noun to mean a general idea and also as an adjective to mean general or approximate.

To say to probably, about, approximately both 大概 and 大约 can be used.

Common Phrases

In the following examples both 大概 and 大约 can be used.

To say a general idea use 大概.

Common Phrases

To say a general, rough, or approximate use 大概.

Common Phrases

即上下文无关文法，是一种形式文法（formal grammar）。形式文法是形式语言（formal language）的文法，由一组产生规则 （production rules）组成，描述该形式语言中所有可能的字符串形式。

上面这段话比价令人费解，我理解，就是每个句子的产生都遵循着一定的规则（规则学习的理念）。在这里面有几个概念：

1. 终止符：可以理解为基础符号，词法符号，是不可替 代的，天然存在，不能通过文法规则生成
2. 非终结符，或者句法变量
3. Production rules： grammar 是由终结符集、非终结符集和产生规则共同组 成。产生规则定义了符号之间如何转换替代。规则的左侧是规则头，是可以被替代的符号；右侧是规则体，是具体的内容。

例： S -> cAd A -> a或ab
(a, b, c, d) 为终结符（用小写表示），(S, A) 为非终结符（用大写表示）。 S -> cAd， A -> a或ab表示产生式规则。 S->cAd，然后可以产生"cad"，“cabd” 等符合文法的内容

上下文无关的产生式：

S -> ABC

A -> 人/天

B -> 吃 /下

C -> 雨/雪/饭/肉

英文字母都是非终结符（这里假设ABC 分别表示主谓宾），汉字都是终结符。其中一个句子组合推导过程为：S -> ABC -> 天BC -> 天吃C -> 天吃肉

这个文法可以生成如下句子｛人吃饭，天下雨，人吃肉，天下雪，人下雪，天下饭，天吃肉，……｝，其中有一些搭配在语义上并不恰当：例如“天吃肉”，这里面可以增加一些生成的约束，比如左边是”人“时，才允许它推导出”吃“