The preposition 和hé and 跟gēn
Prepositions 和 hé and 跟gēn have similar meanings, in most scenarios they simply mean “and”, and they can be interchangeable. We often add the adverb 一起yìqǐ (together) as a fixed phrase, the structure of the complete sentence is:
A+ 和/跟+B +（一起）+Verb+Obj.
|她 和/跟 她 的 姐姐 关系 很 好。|
Tā hé /gēn tā de jiějie guānxi hěn hǎo
She and her sister have a close relationship.
我 和/跟 我 丈夫 一起工作。
Wǒ hé/gēn wǒ zhàngfu yìqǐ gōngzuò.
My husband and I work together.
The story with 跟gēn doesn’t stop here, 跟gēn also has other meanings, as a verb it means “follow”，as an adverb it is used to express “with”，for example:
|你 跟 我 走 吧，我 带 你 回 家。|
Nǐ gēn wǒ zǒu ba ，wǒ dài nǐ huí jiā
Go with me, i take you home.
Nǐ míngtiān gēn lǎobǎn chūchāi ma ？
Will you go with the boss on a business trip tomorrow?
Wǒmen yìqǐ gēn Lǐ lǎoshī xué Zhōngwén .
All of us learn Chinese from Teacher Li.
In these sentences, we can use both 跟gēn and 和hé，but 跟gēn is relatively more accurate, since it is a leading/following relationship.
There are also some other phrases with 跟gēn. For example，we can make comparison, to say “A is the same as B”， we can can say,
|我 跟 你 一样 也 喜欢 踢 足球。|
Wǒ gēn nǐ yíyàng yě xǐhuān tī zúqiú.
I am the same as you, i like playing football too.
你 衣服 的 尺码 跟 我 一样。
Nǐ yīfú de chǐmǎ gēn wǒ yíyàng.
The size of your clothes is same as mine.
or to say “comparing with B，A…” ,we can say,
|跟 去 年 比 起来， 今年 冬天 不 算 冷。|
Gēn qù nián bǐ qǐlái ，jīn nián dōngtiān bú suàn lěng
Comparing to last year, this winter is not cold.
跟 大 城市 比 起来，小 城市 生活 更 悠闲。
Gēn dà chéngshì bǐ qǐlái ，xiǎo chéngshì shēnghuó gèng yōuxián.
Comparing to big cities, the life of small cities is more relaxing.
The preposition 对
When using 对duì as a preposition, it means “to” or “towards” an object, for example,
|他 对 每 个 人 都 很 好。|
Tā duì měi gè rén dōu hěn hǎo.
He is good to everybody.
对 这 件 事， 你 有 什么 看法？
Duì zhè jiàn shì ，nǐ yǒu shénme kànfǎ ？
To this incident, what is your opnion?
他 一直 对 中国 武术 很 有 兴趣。
Tā yìzhí duì zhōngguó wǔshù hěn yǒu xìngqù.
He is always very interested in Chinese martial arts.
When we want to say “A tells B …” ，we can use almost any of the three prepositions, except 对duì emphasizes on “one facing another”,
|她 和 我 说 她 爱 我。|
Tā hé wǒ shuō tā ài wǒ.
She told me she loves me.
她 对 我 说 她 爱 我。
Tā duì wǒ shuō tā ài wǒ
Both sentences are technically correct, but the second one is better as in telling someone something to their face, which is more suitable when you tell someone you love them. If you just want to inform someone something, 跟 and 和 should be quite enough.
|我 和/跟 你 说，我 辞职 了。|
Wǒ hé /gēn nǐ shuō ，wǒ cízhí le
I tell you, i quitted my job.