The Subject
In Chinese the most common form of composing a sentence is using subject and predicate sentence elements. Nouns, pronouns, verbs, adjectives, numerals, duplicated measure words, and phrases can all act as subjects. For instance,

跳舞很健康 (tiàowǔ hěn jiànkāng)。Dancing is quite healthy. ("跳舞" is the subject and is also a verb.)

乐观有益于身体健康 (lèguān yǒu yì yú shēntǐ jiànkāng)。Optimism is good for us health. ("乐观" is the subject and is an adjective.)

十三是个不幸运的数字 (shísān shì gè bú xìng yùn de shùzì)。Thirteen is an unlucky number. ("十三" is the subject and is also a numeral.)

The subject is usually at the start of the sentence, expressing the target of a statement.

Adverbial Adjuncts
Adverbial adjuncts are words or phrases that decorate or limit the predicate.

An adverbial adjunct located before a verb predicate.
他昨天去了上海 (tā zuótiān qù le shànghǎi)。He went Shanghai yesterday.
我只有一件毛衣 ( wǒ zhǐyǒu yíjiàn máoyī)。I only have one sweater.

An adverbial adjunct located before an adjective predicate
我很高兴 (wǒ hěn gāoxìng)。I am very happy.
这朵花非常漂亮 (zhè duǒ huā fēicháng piàoliàng)。This flower is quite beautiful.

The adverbial adjunct must be placed before the word modified. All kinds of words and phrases may act as an adverbial adjunct. The structural particle 地 is often placed after an adverbial adjunct. The basic purpose of adverbs is to act as adverbial adjuncts. For instance,
我非常高兴 (wǒ fēicháng gāo xìng)。I am very happy. (The adverb "非常" acting as the adverbial adjunct modifies the predicate "高兴".)

The main purpose of prepositional phrase is also to act as adverbial adjuncts. For instance,
我们从西边走吧 (wǒmen cóng xībiān zǒu ba)。Let’s go there from the west side. (The prepositional phrase "从西边" modifies the verb "走".)

To conclude, nouns, auxiliary verbs, verbs, adjectives, pronouns, coordinative phrases, subject-predicate phrases, endocentric phrases, numeral-measure word phrases, phrases of locality, and set phrases can all act as adverbial adjuncts.

When verbs, dissyllabic adjectives, coordinative phrases, subject-predicate phrases, duplicated numeral-measure word phrases, and set phrases act as the adverbial adjunct ordinarily the particle "地" (de) must be used. For instance,
请大声地读 (qǐng dàshēng de lǎngdú)。Please read loudly. (The verb "大声" acts as the adverbial adjunct.)
我们粗略地看了 (wǒ men cū lüè de kàn le)。We looked roughly. (The dissyllabic adjective "粗略" acts at the adverbial adjunct.)

When adverbs, prepositional phrases, nouns expressing time or place, monosyllabic adjectives, and pronouns act as an adverbial adjunct, in general, "地" should not be used. For instance,
我很喜欢游泳 (wǒ hěn xǐhuān yóuyǒng)。I really like swimming. (Adverb "很" acts as the adverbial adjunct.)