The preposition 对 and it’s patterns
The preposition 对
The preposition 对 
indicates to whom an action is directed.
indicates to whom an action is directed.Scheme
subject
who 1
对
object
who 2
predicate
Pay attention
If the predicate is a verb, we usually do not translate 对.
We also use 对 to express the meaning of “doing something while facing someone”. So it is often used with verbs like 说 or 笑 .
or 笑 .Examples
你对她说了什么？
What did you tell her?
nĭ duì tā shuō le shénme
她对我笑了
She smiled at me
tā duì wŏ xiào le
If the predicate is expressed by an adjective, 对 is usually translated as “doing something towards someone”.
Examples
他对朋友很大方
He is very generous towards his friends
tā duì péngyou hěn dàfang
对 as part of patterns
We may use 对 in the following constructions:
对…的印象
With the construction 对…的印象 , you can talk about one’s impression of something or someone.
, you can talk about one’s impression of something or someone.Scheme
who
whose impression?
对
what/who
about whom? about what?
的印象
Examples
这会影响别人对你的第一印象
It affects people's first impression of you
zhè huì yǐngxiǎng biérén duì nǐ de dìyī yìnxiàng
你对北京的印象如何？
What are your impressions of Beijing?
nǐ duì běijīng de yìnxiàng rúhé
对…过敏
To tell what a person is allergic to, we use the construction 对…过敏 .
.Examples
我对猫过敏
I'm allergic to cats
wǒ duì māo guòmǐn
您有没有对什么东西过敏的情况？
Are you allergic to anything?
nín yǒu méi yǒu duì shénme dōngxi guòmǐn de qíngkuàng