英文關鍵字
1080p
20s
adult
arithmetic
blackboard
book
both
caucasian
chalk
cheerful
class
classroom
cropped
definition
education
elementary
female
hands
hd
high
highdef
holding
lesson
marker
one
person
school
teacher
teaching
woman
writing
young
英文關鍵字
1080p
20s
adult
arithmetic
blackboard
book
both
caucasian
chalk
cheerful
class
classroom
cropped
definition
education
elementary
female
hands
hd
high
highdef
holding
lesson
marker
one
person
school
teacher
teaching
woman
writing
young