皮皮学，免费搜题
登录
搜题
【判断题】
设S为集合，*为定义在S上的一个二元运算，如果代数系（S，*）存在单位元，则代数系（S，*）只能存在一个唯一的单位元。A.
正确
B.
错误
拍照语音搜题，微信中搜索"皮皮学"使用
参考答案：
参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【单选题】To use the machine, first the correct coins, then select the drink you want and press the button.
A.
install
B.
inspect
C.
insert
D.
instruct
【简答题】The woman’s address is _____ Highwood Drive.A. 1723
【单选题】To use the machine, first the correct coins, then select the drink you want and press the button.
A.
cut
B.
evolve
C.
insert
D.
postpone
【单选题】To use the machine, first the correct coins, then select the drink youwant and press the button.
A.
input
B.
insert
C.
submit
D.
enter
【单选题】To use the machine, first the correct coins, then select the drink you want and press the button.
A.
promote
B.
insert
C.
attach
D.
investiagate
【单选题】Use the button to _____________on different selections.
A.
scroll
B.
click
C.
screen
D.
display
【简答题】The teacher’s calmness during the storm _______ the children.
相关题目：